The Tor Browser: netwerk/cache/nsDiskCacheMap.cpp@b8a032363ba2 (annotated)

netwerk/cache/nsDiskCacheMap.cpp@b8a032363ba2 (annotated)

netwerk/cache/nsDiskCacheMap.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* vim:set ts=4 sw=4 sts=4 cin et: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "nsCache.h"
 #include "nsDiskCacheMap.h"
 #include "nsDiskCacheBinding.h"
 #include "nsDiskCacheEntry.h"
 #include "nsDiskCacheDevice.h"
 #include "nsCacheService.h"
 #include <string.h>
 #include "nsPrintfCString.h"
 #include "nsISerializable.h"
 #include "nsSerializationHelper.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/VisualEventTracer.h"
 #include <algorithm>
 using namespace mozilla;
 /******************************************************************************
  *  nsDiskCacheMap
  *****************************************************************************/
 /**
  *  File operations
  */
 nsresult
 nsDiskCacheMap::Open(nsIFile *  cacheDirectory,
                      nsDiskCache::CorruptCacheInfo *  corruptInfo,
                      bool reportCacheCleanTelemetryData)
 {
     NS_ENSURE_ARG_POINTER(corruptInfo);
     // Assume we have an unexpected error until we find otherwise.
     *corruptInfo = nsDiskCache::kUnexpectedError;
     NS_ENSURE_ARG_POINTER(cacheDirectory);
     if (mMapFD)  return NS_ERROR_ALREADY_INITIALIZED;
     mCacheDirectory = cacheDirectory;   // save a reference for ourselves
     // create nsIFile for _CACHE_MAP_
     nsresult rv;
     nsCOMPtr<nsIFile> file;
     rv = cacheDirectory->Clone(getter_AddRefs(file));
     rv = file->AppendNative(NS_LITERAL_CSTRING("_CACHE_MAP_"));
     NS_ENSURE_SUCCESS(rv, rv);
     // open the file - restricted to user, the data could be confidential
     rv = file->OpenNSPRFileDesc(PR_RDWR | PR_CREATE_FILE, 00600, &mMapFD);
     if (NS_FAILED(rv)) {
         *corruptInfo = nsDiskCache::kOpenCacheMapError;
         NS_WARNING("Could not open cache map file");
         return NS_ERROR_FILE_CORRUPTED;
     }
     bool cacheFilesExist = CacheFilesExist();
     rv = NS_ERROR_FILE_CORRUPTED;  // presume the worst
     uint32_t mapSize = PR_Available(mMapFD);
     if (NS_FAILED(InitCacheClean(cacheDirectory,
                                  corruptInfo,
                                  reportCacheCleanTelemetryData))) {
         // corruptInfo is set in the call to InitCacheClean
         goto error_exit;
     }
     // check size of map file
     if (mapSize == 0) {  // creating a new _CACHE_MAP_
         // block files shouldn't exist if we're creating the _CACHE_MAP_
         if (cacheFilesExist) {
             *corruptInfo = nsDiskCache::kBlockFilesShouldNotExist;
             goto error_exit;
         }
         if (NS_FAILED(CreateCacheSubDirectories())) {
             *corruptInfo = nsDiskCache::kCreateCacheSubdirectories;
             goto error_exit;
         }
         // create the file - initialize in memory
         memset(&mHeader, 0, sizeof(nsDiskCacheHeader));
         mHeader.mVersion = nsDiskCache::kCurrentVersion;
         mHeader.mRecordCount = kMinRecordCount;
         mRecordArray = (nsDiskCacheRecord *)
             PR_CALLOC(mHeader.mRecordCount * sizeof(nsDiskCacheRecord));
         if (!mRecordArray) {
             *corruptInfo = nsDiskCache::kOutOfMemory;
             rv = NS_ERROR_OUT_OF_MEMORY;
             goto error_exit;
         }
     } else if (mapSize >= sizeof(nsDiskCacheHeader)) {  // read existing _CACHE_MAP_
         // if _CACHE_MAP_ exists, so should the block files
         if (!cacheFilesExist) {
             *corruptInfo = nsDiskCache::kBlockFilesShouldExist;
             goto error_exit;
         }
         CACHE_LOG_DEBUG(("CACHE: nsDiskCacheMap::Open [this=%p] reading map", this));
         // read the header
         uint32_t bytesRead = PR_Read(mMapFD, &mHeader, sizeof(nsDiskCacheHeader));
         if (sizeof(nsDiskCacheHeader) != bytesRead) {
             *corruptInfo = nsDiskCache::kHeaderSizeNotRead;
             goto error_exit;
         }
         mHeader.Unswap();
         if (mHeader.mIsDirty) {
             *corruptInfo = nsDiskCache::kHeaderIsDirty;
             goto error_exit;
         }
         if (mHeader.mVersion != nsDiskCache::kCurrentVersion) {
             *corruptInfo = nsDiskCache::kVersionMismatch;
             goto error_exit;
         }
         uint32_t recordArraySize =
                 mHeader.mRecordCount * sizeof(nsDiskCacheRecord);
         if (mapSize < recordArraySize + sizeof(nsDiskCacheHeader)) {
             *corruptInfo = nsDiskCache::kRecordsIncomplete;
             goto error_exit;
         }
         // Get the space for the records
         mRecordArray = (nsDiskCacheRecord *) PR_MALLOC(recordArraySize);
         if (!mRecordArray) {
             *corruptInfo = nsDiskCache::kOutOfMemory;
             rv = NS_ERROR_OUT_OF_MEMORY;
             goto error_exit;
         }
         // Read the records
         bytesRead = PR_Read(mMapFD, mRecordArray, recordArraySize);
         if (bytesRead < recordArraySize) {
             *corruptInfo = nsDiskCache::kNotEnoughToRead;
             goto error_exit;
         }
         // Unswap each record
         int32_t total = 0;
         for (int32_t i = 0; i < mHeader.mRecordCount; ++i) {
             if (mRecordArray[i].HashNumber()) {
 #if defined(IS_LITTLE_ENDIAN)
                 mRecordArray[i].Unswap();
 #endif
                 total ++;
             }
         }
         // verify entry count
         if (total != mHeader.mEntryCount) {
             *corruptInfo = nsDiskCache::kEntryCountIncorrect;
             goto error_exit;
         }
     } else {
         *corruptInfo = nsDiskCache::kHeaderIncomplete;
         goto error_exit;
     }
     rv = OpenBlockFiles(corruptInfo);
     if (NS_FAILED(rv)) {
         // corruptInfo is set in the call to OpenBlockFiles
         goto error_exit;
     }
     // set dirty bit and flush header
     mHeader.mIsDirty    = true;
     rv = FlushHeader();
     if (NS_FAILED(rv)) {
         *corruptInfo = nsDiskCache::kFlushHeaderError;
         goto error_exit;
     }
     Telemetry::Accumulate(Telemetry::HTTP_DISK_CACHE_OVERHEAD,
                           (uint32_t)SizeOfExcludingThis(moz_malloc_size_of));
     *corruptInfo = nsDiskCache::kNotCorrupt;
     return NS_OK;
 error_exit:
     (void) Close(false);
     return rv;
 }
 nsresult
 nsDiskCacheMap::Close(bool flush)
 {
     nsCacheService::AssertOwnsLock();
     nsresult  rv = NS_OK;
     // Cancel any pending cache validation event, the FlushRecords call below
     // will validate the cache.
     if (mCleanCacheTimer) {
         mCleanCacheTimer->Cancel();
     }
     // If cache map file and its block files are still open, close them
     if (mMapFD) {
         // close block files
         rv = CloseBlockFiles(flush);
         if (NS_SUCCEEDED(rv) && flush && mRecordArray) {
             // write the map records
             rv = FlushRecords(false);   // don't bother swapping buckets back
             if (NS_SUCCEEDED(rv)) {
                 // clear dirty bit
                 mHeader.mIsDirty = false;
                 rv = FlushHeader();
             }
         }
         if ((PR_Close(mMapFD) != PR_SUCCESS) && (NS_SUCCEEDED(rv)))
             rv = NS_ERROR_UNEXPECTED;
         mMapFD = nullptr;
     }
     if (mCleanFD) {
         PR_Close(mCleanFD);
         mCleanFD = nullptr;
     }
     PR_FREEIF(mRecordArray);
     PR_FREEIF(mBuffer);
     mBufferSize = 0;
     return rv;
 }
 nsresult
 nsDiskCacheMap::Trim()
 {
     nsresult rv, rv2 = NS_OK;
     for (int i=0; i < kNumBlockFiles; ++i) {
         rv = mBlockFile[i].Trim();
         if (NS_FAILED(rv))  rv2 = rv;   // if one or more errors, report at least one
     }
     // Try to shrink the records array
     rv = ShrinkRecords();
     if (NS_FAILED(rv))  rv2 = rv;   // if one or more errors, report at least one
     return rv2;
 }
 nsresult
 nsDiskCacheMap::FlushHeader()
 {
     if (!mMapFD)  return NS_ERROR_NOT_AVAILABLE;
     // seek to beginning of cache map
     int32_t filePos = PR_Seek(mMapFD, 0, PR_SEEK_SET);
     if (filePos != 0)  return NS_ERROR_UNEXPECTED;
     // write the header
     mHeader.Swap();
     int32_t bytesWritten = PR_Write(mMapFD, &mHeader, sizeof(nsDiskCacheHeader));
     mHeader.Unswap();
     if (sizeof(nsDiskCacheHeader) != bytesWritten) {
         return NS_ERROR_UNEXPECTED;
     }
     PRStatus err = PR_Sync(mMapFD);
     if (err != PR_SUCCESS) return NS_ERROR_UNEXPECTED;
     // If we have a clean header then revalidate the cache clean file
     if (!mHeader.mIsDirty) {
         RevalidateCache();
     }
     return NS_OK;
 }
 nsresult
 nsDiskCacheMap::FlushRecords(bool unswap)
 {
     if (!mMapFD)  return NS_ERROR_NOT_AVAILABLE;
     // seek to beginning of buckets
     int32_t filePos = PR_Seek(mMapFD, sizeof(nsDiskCacheHeader), PR_SEEK_SET);
     if (filePos != sizeof(nsDiskCacheHeader))
         return NS_ERROR_UNEXPECTED;
 #if defined(IS_LITTLE_ENDIAN)
     // Swap each record
     for (int32_t i = 0; i < mHeader.mRecordCount; ++i) {
         if (mRecordArray[i].HashNumber())
             mRecordArray[i].Swap();
     }
 #endif
     int32_t recordArraySize = sizeof(nsDiskCacheRecord) * mHeader.mRecordCount;
     int32_t bytesWritten = PR_Write(mMapFD, mRecordArray, recordArraySize);
     if (bytesWritten != recordArraySize)
         return NS_ERROR_UNEXPECTED;
 #if defined(IS_LITTLE_ENDIAN)
     if (unswap) {
         // Unswap each record
         for (int32_t i = 0; i < mHeader.mRecordCount; ++i) {
             if (mRecordArray[i].HashNumber())
                 mRecordArray[i].Unswap();
         }
     }
 #endif
     return NS_OK;
 }
 /**
  *  Record operations
  */
 uint32_t
 nsDiskCacheMap::GetBucketRank(uint32_t bucketIndex, uint32_t targetRank)
 {
     nsDiskCacheRecord * records = GetFirstRecordInBucket(bucketIndex);
     uint32_t            rank = 0;
     for (int i = mHeader.mBucketUsage[bucketIndex]-1; i >= 0; i--) {
         if ((rank < records[i].EvictionRank()) &&
             ((targetRank == 0) || (records[i].EvictionRank() < targetRank)))
                 rank = records[i].EvictionRank();
     }
     return rank;
 }
 nsresult
 nsDiskCacheMap::GrowRecords()
 {
     if (mHeader.mRecordCount >= mMaxRecordCount)
         return NS_OK;
     CACHE_LOG_DEBUG(("CACHE: GrowRecords\n"));
     // Resize the record array
     int32_t newCount = mHeader.mRecordCount << 1;
     if (newCount > mMaxRecordCount)
         newCount = mMaxRecordCount;
     nsDiskCacheRecord *newArray = (nsDiskCacheRecord *)
             PR_REALLOC(mRecordArray, newCount * sizeof(nsDiskCacheRecord));
     if (!newArray)
         return NS_ERROR_OUT_OF_MEMORY;
     // Space out the buckets
     uint32_t oldRecordsPerBucket = GetRecordsPerBucket();
     uint32_t newRecordsPerBucket = newCount / kBuckets;
     // Work from back to space out each bucket to the new array
     for (int bucketIndex = kBuckets - 1; bucketIndex >= 0; --bucketIndex) {
         // Move bucket
         nsDiskCacheRecord *newRecords = newArray + bucketIndex * newRecordsPerBucket;
         const uint32_t count = mHeader.mBucketUsage[bucketIndex];
         memmove(newRecords,
                 newArray + bucketIndex * oldRecordsPerBucket,
                 count * sizeof(nsDiskCacheRecord));
         // clear unused records
         memset(newRecords + count, 0,
                (newRecordsPerBucket - count) * sizeof(nsDiskCacheRecord));
     }
     // Set as the new record array
     mRecordArray = newArray;
     mHeader.mRecordCount = newCount;
     InvalidateCache();
     return NS_OK;
 }
 nsresult
 nsDiskCacheMap::ShrinkRecords()
 {
     if (mHeader.mRecordCount <= kMinRecordCount)
         return NS_OK;
     CACHE_LOG_DEBUG(("CACHE: ShrinkRecords\n"));
     // Verify if we can shrink the record array: all buckets must be less than
     // 1/2 filled
     uint32_t maxUsage = 0, bucketIndex;
     for (bucketIndex = 0; bucketIndex < kBuckets; ++bucketIndex) {
         if (maxUsage < mHeader.mBucketUsage[bucketIndex])
             maxUsage = mHeader.mBucketUsage[bucketIndex];
     }
     // Determine new bucket size, halve size until maxUsage
     uint32_t oldRecordsPerBucket = GetRecordsPerBucket();
     uint32_t newRecordsPerBucket = oldRecordsPerBucket;
     while (maxUsage < (newRecordsPerBucket >> 1))
         newRecordsPerBucket >>= 1;
     if (newRecordsPerBucket < (kMinRecordCount / kBuckets))
         newRecordsPerBucket = (kMinRecordCount / kBuckets);
     NS_ASSERTION(newRecordsPerBucket <= oldRecordsPerBucket,
                  "ShrinkRecords() can't grow records!");
     if (newRecordsPerBucket == oldRecordsPerBucket)
         return NS_OK;
     // Move the buckets close to each other
     for (bucketIndex = 1; bucketIndex < kBuckets; ++bucketIndex) {
         // Move bucket
         memmove(mRecordArray + bucketIndex * newRecordsPerBucket,
                 mRecordArray + bucketIndex * oldRecordsPerBucket,
                 newRecordsPerBucket * sizeof(nsDiskCacheRecord));
     }
     // Shrink the record array memory block itself
     uint32_t newCount = newRecordsPerBucket * kBuckets;
     nsDiskCacheRecord* newArray = (nsDiskCacheRecord *)
             PR_REALLOC(mRecordArray, newCount * sizeof(nsDiskCacheRecord));
     if (!newArray)
         return NS_ERROR_OUT_OF_MEMORY;
     // Set as the new record array
     mRecordArray = newArray;
     mHeader.mRecordCount = newCount;
     InvalidateCache();
     return NS_OK;
 }
 nsresult
 nsDiskCacheMap::AddRecord( nsDiskCacheRecord *  mapRecord,
                            nsDiskCacheRecord *  oldRecord)
 {
     CACHE_LOG_DEBUG(("CACHE: AddRecord [%x]\n", mapRecord->HashNumber()));
     const uint32_t      hashNumber = mapRecord->HashNumber();
     const uint32_t      bucketIndex = GetBucketIndex(hashNumber);
     const uint32_t      count = mHeader.mBucketUsage[bucketIndex];
     oldRecord->SetHashNumber(0);  // signify no record
     if (count == GetRecordsPerBucket()) {
         // Ignore failure to grow the record space, we will then reuse old records
         GrowRecords();
     }
     nsDiskCacheRecord * records = GetFirstRecordInBucket(bucketIndex);
     if (count < GetRecordsPerBucket()) {
         // stick the new record at the end
         records[count] = *mapRecord;
         mHeader.mEntryCount++;
         mHeader.mBucketUsage[bucketIndex]++;
         if (mHeader.mEvictionRank[bucketIndex] < mapRecord->EvictionRank())
             mHeader.mEvictionRank[bucketIndex] = mapRecord->EvictionRank();
         InvalidateCache();
     } else {
         // Find the record with the highest eviction rank
         nsDiskCacheRecord * mostEvictable = &records[0];
         for (int i = count-1; i > 0; i--) {
             if (records[i].EvictionRank() > mostEvictable->EvictionRank())
                 mostEvictable = &records[i];
         }
         *oldRecord     = *mostEvictable;    // i == GetRecordsPerBucket(), so
                                             // evict the mostEvictable
         *mostEvictable = *mapRecord;        // replace it with the new record
         // check if we need to update mostEvictable entry in header
         if (mHeader.mEvictionRank[bucketIndex] < mapRecord->EvictionRank())
             mHeader.mEvictionRank[bucketIndex] = mapRecord->EvictionRank();
         if (oldRecord->EvictionRank() >= mHeader.mEvictionRank[bucketIndex])
             mHeader.mEvictionRank[bucketIndex] = GetBucketRank(bucketIndex, 0);
         InvalidateCache();
     }
     NS_ASSERTION(mHeader.mEvictionRank[bucketIndex] == GetBucketRank(bucketIndex, 0),
                  "eviction rank out of sync");
     return NS_OK;
 }
 nsresult
 nsDiskCacheMap::UpdateRecord( nsDiskCacheRecord *  mapRecord)
 {
     CACHE_LOG_DEBUG(("CACHE: UpdateRecord [%x]\n", mapRecord->HashNumber()));
     const uint32_t      hashNumber = mapRecord->HashNumber();
     const uint32_t      bucketIndex = GetBucketIndex(hashNumber);
     nsDiskCacheRecord * records = GetFirstRecordInBucket(bucketIndex);
     for (int i = mHeader.mBucketUsage[bucketIndex]-1; i >= 0; i--) {
         if (records[i].HashNumber() == hashNumber) {
             const uint32_t oldRank = records[i].EvictionRank();
             // stick the new record here
             records[i] = *mapRecord;
             // update eviction rank in header if necessary
             if (mHeader.mEvictionRank[bucketIndex] < mapRecord->EvictionRank())
                 mHeader.mEvictionRank[bucketIndex] = mapRecord->EvictionRank();
             else if (mHeader.mEvictionRank[bucketIndex] == oldRank)
                 mHeader.mEvictionRank[bucketIndex] = GetBucketRank(bucketIndex, 0);
             InvalidateCache();
 NS_ASSERTION(mHeader.mEvictionRank[bucketIndex] == GetBucketRank(bucketIndex, 0),
              "eviction rank out of sync");
             return NS_OK;
         }
     }
     NS_NOTREACHED("record not found");
     return NS_ERROR_UNEXPECTED;
 }
 nsresult
 nsDiskCacheMap::FindRecord( uint32_t  hashNumber, nsDiskCacheRecord *  result)
 {
     const uint32_t      bucketIndex = GetBucketIndex(hashNumber);
     nsDiskCacheRecord * records = GetFirstRecordInBucket(bucketIndex);
     for (int i = mHeader.mBucketUsage[bucketIndex]-1; i >= 0; i--) {
         if (records[i].HashNumber() == hashNumber) {
             *result = records[i];    // copy the record
             NS_ASSERTION(result->ValidRecord(), "bad cache map record");
             return NS_OK;
         }
     }
     return NS_ERROR_CACHE_KEY_NOT_FOUND;
 }
 nsresult
 nsDiskCacheMap::DeleteRecord( nsDiskCacheRecord *  mapRecord)
 {
     CACHE_LOG_DEBUG(("CACHE: DeleteRecord [%x]\n", mapRecord->HashNumber()));
     const uint32_t      hashNumber = mapRecord->HashNumber();
     const uint32_t      bucketIndex = GetBucketIndex(hashNumber);
     nsDiskCacheRecord * records = GetFirstRecordInBucket(bucketIndex);
     uint32_t            last = mHeader.mBucketUsage[bucketIndex]-1;
     for (int i = last; i >= 0; i--) {
         if (records[i].HashNumber() == hashNumber) {
             // found it, now delete it.
             uint32_t  evictionRank = records[i].EvictionRank();
             NS_ASSERTION(evictionRank == mapRecord->EvictionRank(),
                          "evictionRank out of sync");
             // if not the last record, shift last record into opening
             records[i] = records[last];
             records[last].SetHashNumber(0); // clear last record
             mHeader.mBucketUsage[bucketIndex] = last;
             mHeader.mEntryCount--;
             // update eviction rank
             uint32_t  bucketIndex = GetBucketIndex(mapRecord->HashNumber());
             if (mHeader.mEvictionRank[bucketIndex] <= evictionRank) {
                 mHeader.mEvictionRank[bucketIndex] = GetBucketRank(bucketIndex, 0);
             }
             InvalidateCache();
             NS_ASSERTION(mHeader.mEvictionRank[bucketIndex] ==
                          GetBucketRank(bucketIndex, 0), "eviction rank out of sync");
             return NS_OK;
         }
     }
     return NS_ERROR_UNEXPECTED;
 }
 int32_t
 nsDiskCacheMap::VisitEachRecord(uint32_t                    bucketIndex,
                                 nsDiskCacheRecordVisitor *  visitor,
                                 uint32_t                    evictionRank)
 {
     int32_t             rv = kVisitNextRecord;
     uint32_t            count = mHeader.mBucketUsage[bucketIndex];
     nsDiskCacheRecord * records = GetFirstRecordInBucket(bucketIndex);
     // call visitor for each entry (matching any eviction rank)
     for (int i = count-1; i >= 0; i--) {
         if (evictionRank > records[i].EvictionRank()) continue;
         rv = visitor->VisitRecord(&records[i]);
         if (rv == kStopVisitingRecords)
             break;    // Stop visiting records
         if (rv == kDeleteRecordAndContinue) {
             --count;
             records[i] = records[count];
             records[count].SetHashNumber(0);
             InvalidateCache();
         }
     }
     if (mHeader.mBucketUsage[bucketIndex] - count != 0) {
         mHeader.mEntryCount -= mHeader.mBucketUsage[bucketIndex] - count;
         mHeader.mBucketUsage[bucketIndex] = count;
         // recalc eviction rank
         mHeader.mEvictionRank[bucketIndex] = GetBucketRank(bucketIndex, 0);
     }
     NS_ASSERTION(mHeader.mEvictionRank[bucketIndex] ==
                  GetBucketRank(bucketIndex, 0), "eviction rank out of sync");
     return rv;
 }
 /**
  *  VisitRecords
  *
  *  Visit every record in cache map in the most convenient order
  */
 nsresult
 nsDiskCacheMap::VisitRecords( nsDiskCacheRecordVisitor *  visitor)
 {
     for (int bucketIndex = 0; bucketIndex < kBuckets; ++bucketIndex) {
         if (VisitEachRecord(bucketIndex, visitor, 0) == kStopVisitingRecords)
             break;
     }
     return NS_OK;
 }
 /**
  *  EvictRecords
  *
  *  Just like VisitRecords, but visits the records in order of their eviction rank
  */
 nsresult
 nsDiskCacheMap::EvictRecords( nsDiskCacheRecordVisitor * visitor)
 {
     uint32_t  tempRank[kBuckets];
     int       bucketIndex = 0;
     // copy eviction rank array
     for (bucketIndex = 0; bucketIndex < kBuckets; ++bucketIndex)
         tempRank[bucketIndex] = mHeader.mEvictionRank[bucketIndex];
     // Maximum number of iterations determined by number of records
     // as a safety limiter for the loop. Use a copy of mHeader.mEntryCount since
     // the value could decrease if some entry is evicted.
     int32_t entryCount = mHeader.mEntryCount;
     for (int n = 0; n < entryCount; ++n) {
         // find bucket with highest eviction rank
         uint32_t    rank  = 0;
         for (int i = 0; i < kBuckets; ++i) {
             if (rank < tempRank[i]) {
                 rank = tempRank[i];
                 bucketIndex = i;
             }
         }
         if (rank == 0) break;  // we've examined all the records
         // visit records in bucket with eviction ranks >= target eviction rank
         if (VisitEachRecord(bucketIndex, visitor, rank) == kStopVisitingRecords)
             break;
         // find greatest rank less than 'rank'
         tempRank[bucketIndex] = GetBucketRank(bucketIndex, rank);
     }
     return NS_OK;
 }
 nsresult
 nsDiskCacheMap::OpenBlockFiles(nsDiskCache::CorruptCacheInfo *  corruptInfo)
 {
     NS_ENSURE_ARG_POINTER(corruptInfo);
     // create nsIFile for block file
     nsCOMPtr<nsIFile> blockFile;
     nsresult rv = NS_OK;
     *corruptInfo = nsDiskCache::kUnexpectedError;
     for (int i = 0; i < kNumBlockFiles; ++i) {
         rv = GetBlockFileForIndex(i, getter_AddRefs(blockFile));
         if (NS_FAILED(rv)) {
             *corruptInfo = nsDiskCache::kCouldNotGetBlockFileForIndex;
             break;
         }
         uint32_t blockSize = GetBlockSizeForIndex(i+1); // +1 to match file selectors 1,2,3
         uint32_t bitMapSize = GetBitMapSizeForIndex(i+1);
         rv = mBlockFile[i].Open(blockFile, blockSize, bitMapSize, corruptInfo);
         if (NS_FAILED(rv)) {
             // corruptInfo was set inside the call to mBlockFile[i].Open
             break;
         }
     }
     // close all files in case of any error
     if (NS_FAILED(rv))
         (void)CloseBlockFiles(false); // we already have an error to report
     return rv;
 }
 nsresult
 nsDiskCacheMap::CloseBlockFiles(bool flush)
 {
     nsresult rv, rv2 = NS_OK;
     for (int i=0; i < kNumBlockFiles; ++i) {
         rv = mBlockFile[i].Close(flush);
         if (NS_FAILED(rv))  rv2 = rv;   // if one or more errors, report at least one
     }
     return rv2;
 }
 bool
 nsDiskCacheMap::CacheFilesExist()
 {
     nsCOMPtr<nsIFile> blockFile;
     nsresult rv;
     for (int i = 0; i < kNumBlockFiles; ++i) {
         bool exists;
         rv = GetBlockFileForIndex(i, getter_AddRefs(blockFile));
         if (NS_FAILED(rv))  return false;
         rv = blockFile->Exists(&exists);
         if (NS_FAILED(rv) || !exists)  return false;
     }
     return true;
 }
 nsresult
 nsDiskCacheMap::CreateCacheSubDirectories()
 {
     if (!mCacheDirectory)
         return NS_ERROR_UNEXPECTED;
     for (int32_t index = 0 ; index < 16 ; index++) {
         nsCOMPtr<nsIFile> file;
         nsresult rv = mCacheDirectory->Clone(getter_AddRefs(file));
         if (NS_FAILED(rv))
             return rv;
         rv = file->AppendNative(nsPrintfCString("%X", index));
         if (NS_FAILED(rv))
             return rv;
         rv = file->Create(nsIFile::DIRECTORY_TYPE, 0700);
         if (NS_FAILED(rv))
             return rv;
     }
     return NS_OK;
 }
 nsDiskCacheEntry *
 nsDiskCacheMap::ReadDiskCacheEntry(nsDiskCacheRecord * record)
 {
     CACHE_LOG_DEBUG(("CACHE: ReadDiskCacheEntry [%x]\n", record->HashNumber()));
     nsresult            rv         = NS_ERROR_UNEXPECTED;
     nsDiskCacheEntry *  diskEntry  = nullptr;
     uint32_t            metaFile   = record->MetaFile();
     int32_t             bytesRead  = 0;
     if (!record->MetaLocationInitialized())  return nullptr;
     if (metaFile == 0) {  // entry/metadata stored in separate file
         // open and read the file
         nsCOMPtr<nsIFile> file;
         rv = GetLocalFileForDiskCacheRecord(record,
                                             nsDiskCache::kMetaData,
                                             false,
                                             getter_AddRefs(file));
         NS_ENSURE_SUCCESS(rv, nullptr);
         CACHE_LOG_DEBUG(("CACHE: nsDiskCacheMap::ReadDiskCacheEntry"
                          "[this=%p] reading disk cache entry", this));
         PRFileDesc * fd = nullptr;
         // open the file - restricted to user, the data could be confidential
         rv = file->OpenNSPRFileDesc(PR_RDONLY, 00600, &fd);
         NS_ENSURE_SUCCESS(rv, nullptr);
         int32_t fileSize = PR_Available(fd);
         if (fileSize < 0) {
             // an error occurred. We could call PR_GetError(), but how would that help?
             rv = NS_ERROR_UNEXPECTED;
         } else {
             rv = EnsureBuffer(fileSize);
             if (NS_SUCCEEDED(rv)) {
                 bytesRead = PR_Read(fd, mBuffer, fileSize);
                 if (bytesRead < fileSize) {
                     rv = NS_ERROR_UNEXPECTED;
                 }
             }
         }
         PR_Close(fd);
         NS_ENSURE_SUCCESS(rv, nullptr);
     } else if (metaFile < (kNumBlockFiles + 1)) {
         // entry/metadata stored in cache block file
         // allocate buffer
         uint32_t blockCount = record->MetaBlockCount();
         bytesRead = blockCount * GetBlockSizeForIndex(metaFile);
         rv = EnsureBuffer(bytesRead);
         NS_ENSURE_SUCCESS(rv, nullptr);
         // read diskEntry, note when the blocks are at the end of file,
         // bytesRead may be less than blockSize*blockCount.
         // But the bytesRead should at least agree with the real disk entry size.
         rv = mBlockFile[metaFile - 1].ReadBlocks(mBuffer,
                                                  record->MetaStartBlock(),
                                                  blockCount,
                                                  &bytesRead);
         NS_ENSURE_SUCCESS(rv, nullptr);
     }
     diskEntry = (nsDiskCacheEntry *)mBuffer;
     diskEntry->Unswap();    // disk to memory
     // Check if calculated size agrees with bytesRead
     if (bytesRead < 0 || (uint32_t)bytesRead < diskEntry->Size())
         return nullptr;
     // Return the buffer containing the diskEntry structure
     return diskEntry;
 }
 /**
  *  CreateDiskCacheEntry(nsCacheEntry * entry)
  *
  *  Prepare an nsCacheEntry for writing to disk
  */
 nsDiskCacheEntry *
 nsDiskCacheMap::CreateDiskCacheEntry(nsDiskCacheBinding *  binding,
                                      uint32_t * aSize)
 {
     nsCacheEntry * entry = binding->mCacheEntry;
     if (!entry)  return nullptr;
     // Store security info, if it is serializable
     nsCOMPtr<nsISupports> infoObj = entry->SecurityInfo();
     nsCOMPtr<nsISerializable> serializable = do_QueryInterface(infoObj);
     if (infoObj && !serializable) return nullptr;
     if (serializable) {
         nsCString info;
         nsresult rv = NS_SerializeToString(serializable, info);
         if (NS_FAILED(rv)) return nullptr;
         rv = entry->SetMetaDataElement("security-info", info.get());
         if (NS_FAILED(rv)) return nullptr;
     }
     uint32_t  keySize  = entry->Key()->Length() + 1;
     uint32_t  metaSize = entry->MetaDataSize();
     uint32_t  size     = sizeof(nsDiskCacheEntry) + keySize + metaSize;
     if (aSize) *aSize = size;
     nsresult rv = EnsureBuffer(size);
     if (NS_FAILED(rv)) return nullptr;
     nsDiskCacheEntry *diskEntry = (nsDiskCacheEntry *)mBuffer;
     diskEntry->mHeaderVersion   = nsDiskCache::kCurrentVersion;
     diskEntry->mMetaLocation    = binding->mRecord.MetaLocation();
     diskEntry->mFetchCount      = entry->FetchCount();
     diskEntry->mLastFetched     = entry->LastFetched();
     diskEntry->mLastModified    = entry->LastModified();
     diskEntry->mExpirationTime  = entry->ExpirationTime();
     diskEntry->mDataSize        = entry->DataSize();
     diskEntry->mKeySize         = keySize;
     diskEntry->mMetaDataSize    = metaSize;
     memcpy(diskEntry->Key(), entry->Key()->get(), keySize);
     rv = entry->FlattenMetaData(diskEntry->MetaData(), metaSize);
     if (NS_FAILED(rv)) return nullptr;
     return diskEntry;
 }
 nsresult
 nsDiskCacheMap::WriteDiskCacheEntry(nsDiskCacheBinding *  binding)
 {
     CACHE_LOG_DEBUG(("CACHE: WriteDiskCacheEntry [%x]\n",
         binding->mRecord.HashNumber()));
     mozilla::eventtracer::AutoEventTracer writeDiskCacheEntry(
         binding->mCacheEntry,
         mozilla::eventtracer::eExec,
         mozilla::eventtracer::eDone,
         "net::cache::WriteDiskCacheEntry");
     nsresult            rv        = NS_OK;
     uint32_t            size;
     nsDiskCacheEntry *  diskEntry =  CreateDiskCacheEntry(binding, &size);
     if (!diskEntry)  return NS_ERROR_UNEXPECTED;
     uint32_t  fileIndex = CalculateFileIndex(size);
     // Deallocate old storage if necessary
     if (binding->mRecord.MetaLocationInitialized()) {
         // we have existing storage
         if ((binding->mRecord.MetaFile() == 0) &&
             (fileIndex == 0)) {  // keeping the separate file
             // just decrement total
             DecrementTotalSize(binding->mRecord.MetaFileSize());
             NS_ASSERTION(binding->mRecord.MetaFileGeneration() == binding->mGeneration,
                          "generations out of sync");
         } else {
             rv = DeleteStorage(&binding->mRecord, nsDiskCache::kMetaData);
             NS_ENSURE_SUCCESS(rv, rv);
         }
     }
     binding->mRecord.SetEvictionRank(ULONG_MAX - SecondsFromPRTime(PR_Now()));
     // write entry data to disk cache block file
     diskEntry->Swap();
     if (fileIndex != 0) {
         while (1) {
             uint32_t  blockSize = GetBlockSizeForIndex(fileIndex);
             uint32_t  blocks    = ((size - 1) / blockSize) + 1;
             int32_t startBlock;
             rv = mBlockFile[fileIndex - 1].WriteBlocks(diskEntry, size, blocks,
                                                        &startBlock);
             if (NS_SUCCEEDED(rv)) {
                 // update binding and cache map record
                 binding->mRecord.SetMetaBlocks(fileIndex, startBlock, blocks);
                 rv = UpdateRecord(&binding->mRecord);
                 NS_ENSURE_SUCCESS(rv, rv);
                 // XXX we should probably write out bucket ourselves
                 IncrementTotalSize(blocks, blockSize);
                 break;
             }
             if (fileIndex == kNumBlockFiles) {
                 fileIndex = 0; // write data to separate file
                 break;
             }
             // try next block file
             fileIndex++;
         }
     }
     if (fileIndex == 0) {
         // Write entry data to separate file
         uint32_t metaFileSizeK = ((size + 0x03FF) >> 10); // round up to nearest 1k
         if (metaFileSizeK > kMaxDataSizeK)
             metaFileSizeK = kMaxDataSizeK;
         binding->mRecord.SetMetaFileGeneration(binding->mGeneration);
         binding->mRecord.SetMetaFileSize(metaFileSizeK);
         rv = UpdateRecord(&binding->mRecord);
         NS_ENSURE_SUCCESS(rv, rv);
         nsCOMPtr<nsIFile> localFile;
         rv = GetLocalFileForDiskCacheRecord(&binding->mRecord,
                                             nsDiskCache::kMetaData,
                                             true,
                                             getter_AddRefs(localFile));
         NS_ENSURE_SUCCESS(rv, rv);
         // open the file
         PRFileDesc * fd;
         // open the file - restricted to user, the data could be confidential
         rv = localFile->OpenNSPRFileDesc(PR_RDWR | PR_TRUNCATE | PR_CREATE_FILE, 00600, &fd);
         NS_ENSURE_SUCCESS(rv, rv);
         // write the file
         int32_t bytesWritten = PR_Write(fd, diskEntry, size);
         PRStatus err = PR_Close(fd);
         if ((bytesWritten != (int32_t)size) || (err != PR_SUCCESS)) {
             return NS_ERROR_UNEXPECTED;
         }
         IncrementTotalSize(metaFileSizeK);
     }
     return rv;
 }
 nsresult
 nsDiskCacheMap::ReadDataCacheBlocks(nsDiskCacheBinding * binding, char * buffer, uint32_t size)
 {
     CACHE_LOG_DEBUG(("CACHE: ReadDataCacheBlocks [%x size=%u]\n",
         binding->mRecord.HashNumber(), size));
     uint32_t  fileIndex = binding->mRecord.DataFile();
     int32_t   readSize = size;
     nsresult rv = mBlockFile[fileIndex - 1].ReadBlocks(buffer,
                                                        binding->mRecord.DataStartBlock(),
                                                        binding->mRecord.DataBlockCount(),
                                                        &readSize);
     NS_ENSURE_SUCCESS(rv, rv);
     if (readSize < (int32_t)size) {
         rv = NS_ERROR_UNEXPECTED;
     }
     return rv;
 }
 nsresult
 nsDiskCacheMap::WriteDataCacheBlocks(nsDiskCacheBinding * binding, char * buffer, uint32_t size)
 {
     CACHE_LOG_DEBUG(("CACHE: WriteDataCacheBlocks [%x size=%u]\n",
         binding->mRecord.HashNumber(), size));
     mozilla::eventtracer::AutoEventTracer writeDataCacheBlocks(
         binding->mCacheEntry,
         mozilla::eventtracer::eExec,
         mozilla::eventtracer::eDone,
         "net::cache::WriteDataCacheBlocks");
     nsresult  rv = NS_OK;
     // determine block file & number of blocks
     uint32_t  fileIndex  = CalculateFileIndex(size);
     uint32_t  blockCount = 0;
     int32_t   startBlock = 0;
     if (size > 0) {
         // if fileIndex is 0, bad things happen below, which makes gcc 4.7
         // complain, but it's not supposed to happen. See bug 854105.
         MOZ_ASSERT(fileIndex);
         while (fileIndex) {
             uint32_t  blockSize  = GetBlockSizeForIndex(fileIndex);
             blockCount = ((size - 1) / blockSize) + 1;
             rv = mBlockFile[fileIndex - 1].WriteBlocks(buffer, size, blockCount,
                                                        &startBlock);
             if (NS_SUCCEEDED(rv)) {
                 IncrementTotalSize(blockCount, blockSize);
                 break;
             }
             if (fileIndex == kNumBlockFiles)
                 return rv;
             fileIndex++;
         }
     }
     // update binding and cache map record
     binding->mRecord.SetDataBlocks(fileIndex, startBlock, blockCount);
     if (!binding->mDoomed) {
         rv = UpdateRecord(&binding->mRecord);
     }
     return rv;
 }
 nsresult
 nsDiskCacheMap::DeleteStorage(nsDiskCacheRecord * record)
 {
     nsresult  rv1 = DeleteStorage(record, nsDiskCache::kData);
     nsresult  rv2 = DeleteStorage(record, nsDiskCache::kMetaData);
     return NS_FAILED(rv1) ? rv1 : rv2;
 }
 nsresult
 nsDiskCacheMap::DeleteStorage(nsDiskCacheRecord * record, bool metaData)
 {
     CACHE_LOG_DEBUG(("CACHE: DeleteStorage [%x %u]\n", record->HashNumber(),
         metaData));
     nsresult    rv = NS_ERROR_UNEXPECTED;
     uint32_t    fileIndex = metaData ? record->MetaFile() : record->DataFile();
     nsCOMPtr<nsIFile> file;
     if (fileIndex == 0) {
         // delete the file
         uint32_t  sizeK = metaData ? record->MetaFileSize() : record->DataFileSize();
         // XXX if sizeK == USHRT_MAX, stat file for actual size
         rv = GetFileForDiskCacheRecord(record, metaData, false, getter_AddRefs(file));
         if (NS_SUCCEEDED(rv)) {
             rv = file->Remove(false);    // false == non-recursive
         }
         DecrementTotalSize(sizeK);
     } else if (fileIndex < (kNumBlockFiles + 1)) {
         // deallocate blocks
         uint32_t  startBlock = metaData ? record->MetaStartBlock() : record->DataStartBlock();
         uint32_t  blockCount = metaData ? record->MetaBlockCount() : record->DataBlockCount();
         rv = mBlockFile[fileIndex - 1].DeallocateBlocks(startBlock, blockCount);
         DecrementTotalSize(blockCount, GetBlockSizeForIndex(fileIndex));
     }
     if (metaData)  record->ClearMetaLocation();
     else           record->ClearDataLocation();
     return rv;
 }
 nsresult
 nsDiskCacheMap::GetFileForDiskCacheRecord(nsDiskCacheRecord * record,
                                           bool                meta,
                                           bool                createPath,
                                           nsIFile **          result)
 {
     if (!mCacheDirectory)  return NS_ERROR_NOT_AVAILABLE;
     nsCOMPtr<nsIFile> file;
     nsresult rv = mCacheDirectory->Clone(getter_AddRefs(file));
     if (NS_FAILED(rv))  return rv;
     uint32_t hash = record->HashNumber();
     // The file is stored under subdirectories according to the hash number:
     // 0x01234567 -> 0/12/
     rv = file->AppendNative(nsPrintfCString("%X", hash >> 28));
     if (NS_FAILED(rv))  return rv;
     rv = file->AppendNative(nsPrintfCString("%02X", (hash >> 20) & 0xFF));
     if (NS_FAILED(rv))  return rv;
     bool exists;
     if (createPath && (NS_FAILED(file->Exists(&exists)) || !exists)) {
         rv = file->Create(nsIFile::DIRECTORY_TYPE, 0700);
         if (NS_FAILED(rv))  return rv;
     }
     int16_t generation = record->Generation();
     char name[32];
     // Cut the beginning of the hash that was used in the path
     ::sprintf(name, "%05X%c%02X", hash & 0xFFFFF, (meta ? 'm' : 'd'),
               generation);
     rv = file->AppendNative(nsDependentCString(name));
     if (NS_FAILED(rv))  return rv;
     NS_IF_ADDREF(*result = file);
     return rv;
 }
 nsresult
 nsDiskCacheMap::GetLocalFileForDiskCacheRecord(nsDiskCacheRecord * record,
                                                bool                meta,
                                                bool                createPath,
                                                nsIFile **          result)
 {
     nsCOMPtr<nsIFile> file;
     nsresult rv = GetFileForDiskCacheRecord(record,
                                             meta,
                                             createPath,
                                             getter_AddRefs(file));
     if (NS_FAILED(rv))  return rv;
     NS_IF_ADDREF(*result = file);
     return rv;
 }
 nsresult
 nsDiskCacheMap::GetBlockFileForIndex(uint32_t index, nsIFile ** result)
 {
     if (!mCacheDirectory)  return NS_ERROR_NOT_AVAILABLE;
     nsCOMPtr<nsIFile> file;
     nsresult rv = mCacheDirectory->Clone(getter_AddRefs(file));
     if (NS_FAILED(rv))  return rv;
     char name[32];
     ::sprintf(name, "_CACHE_%03d_", index + 1);
     rv = file->AppendNative(nsDependentCString(name));
     if (NS_FAILED(rv))  return rv;
     NS_IF_ADDREF(*result = file);
     return rv;
 }
 uint32_t
 nsDiskCacheMap::CalculateFileIndex(uint32_t size)
 {
     // We prefer to use block file with larger block if the wasted space would
     // be the same. E.g. store entry with size of 3073 bytes in 1 4K-block
     // instead of in 4 1K-blocks.
     if (size <= 3 * BLOCK_SIZE_FOR_INDEX(1))  return 1;
     if (size <= 3 * BLOCK_SIZE_FOR_INDEX(2))  return 2;
     if (size <= 4 * BLOCK_SIZE_FOR_INDEX(3))  return 3;
     return 0;
 }
 nsresult
 nsDiskCacheMap::EnsureBuffer(uint32_t bufSize)
 {
     if (mBufferSize < bufSize) {
         char * buf = (char *)PR_REALLOC(mBuffer, bufSize);
         if (!buf) {
             mBufferSize = 0;
             return NS_ERROR_OUT_OF_MEMORY;
         }
         mBuffer = buf;
         mBufferSize = bufSize;
     }
     return NS_OK;
 }
 void
 nsDiskCacheMap::NotifyCapacityChange(uint32_t capacity)
 {
   // Heuristic 1. average cache entry size is probably around 1KB
   // Heuristic 2. we don't want more than 32MB reserved to store the record
   //              map in memory.
   const int32_t RECORD_COUNT_LIMIT = 32 * 1024 * 1024 / sizeof(nsDiskCacheRecord);
   int32_t maxRecordCount = std::min(int32_t(capacity), RECORD_COUNT_LIMIT);
   if (mMaxRecordCount < maxRecordCount) {
     // We can only grow
     mMaxRecordCount = maxRecordCount;
   }
 }
 size_t
 nsDiskCacheMap::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf)
 {
   size_t usage = aMallocSizeOf(mRecordArray);
   usage += aMallocSizeOf(mBuffer);
   usage += aMallocSizeOf(mMapFD);
   usage += aMallocSizeOf(mCleanFD);
   usage += aMallocSizeOf(mCacheDirectory);
   usage += aMallocSizeOf(mCleanCacheTimer);
   for (int i = 0; i < kNumBlockFiles; i++) {
     usage += mBlockFile[i].SizeOfExcludingThis(aMallocSizeOf);
   }
   return usage;
 }
 nsresult
 nsDiskCacheMap::InitCacheClean(nsIFile *  cacheDirectory,
                                nsDiskCache::CorruptCacheInfo *  corruptInfo,
                                bool reportCacheCleanTelemetryData)
 {
     // The _CACHE_CLEAN_ file will be used in the future to determine
     // if the cache is clean or not.
     bool cacheCleanFileExists = false;
     nsCOMPtr<nsIFile> cacheCleanFile;
     nsresult rv = cacheDirectory->GetParent(getter_AddRefs(cacheCleanFile));
     if (NS_SUCCEEDED(rv)) {
         rv = cacheCleanFile->AppendNative(
                  NS_LITERAL_CSTRING("_CACHE_CLEAN_"));
         if (NS_SUCCEEDED(rv)) {
             // Check if the file already exists, if it does, we will later read the
             // value and report it to telemetry.
             cacheCleanFile->Exists(&cacheCleanFileExists);
         }
     }
     if (NS_FAILED(rv)) {
         NS_WARNING("Could not build cache clean file path");
         *corruptInfo = nsDiskCache::kCacheCleanFilePathError;
         return rv;
     }
     // Make sure the _CACHE_CLEAN_ file exists
     rv = cacheCleanFile->OpenNSPRFileDesc(PR_RDWR | PR_CREATE_FILE,
 , &mCleanFD);
     if (NS_FAILED(rv)) {
         NS_WARNING("Could not open cache clean file");
         *corruptInfo = nsDiskCache::kCacheCleanOpenFileError;
         return rv;
     }
     if (cacheCleanFileExists) {
         char clean = '0';
         int32_t bytesRead = PR_Read(mCleanFD, &clean, 1);
         if (bytesRead != 1) {
             NS_WARNING("Could not read _CACHE_CLEAN_ file contents");
         } else if (reportCacheCleanTelemetryData) {
             Telemetry::Accumulate(Telemetry::DISK_CACHE_REDUCTION_TRIAL,
                                   clean == '1' ? 1 : 0);
         }
     }
     // Create a timer that will be used to validate the cache
     // as long as an activity threshold was met
     mCleanCacheTimer = do_CreateInstance("@mozilla.org/timer;1", &rv);
     if (NS_SUCCEEDED(rv)) {
         mCleanCacheTimer->SetTarget(nsCacheService::GlobalInstance()->mCacheIOThread);
         rv = ResetCacheTimer();
     }
     if (NS_FAILED(rv)) {
         NS_WARNING("Could not create cache clean timer");
         mCleanCacheTimer = nullptr;
         *corruptInfo = nsDiskCache::kCacheCleanTimerError;
         return rv;
     }
     return NS_OK;
 }
 nsresult
 nsDiskCacheMap::WriteCacheClean(bool clean)
 {
     nsCacheService::AssertOwnsLock();
     if (!mCleanFD) {
         NS_WARNING("Cache clean file is not open!");
         return NS_ERROR_FAILURE;
     }
     CACHE_LOG_DEBUG(("CACHE: WriteCacheClean: %d\n", clean? 1 : 0));
     // I'm using a simple '1' or '0' to denote cache clean
     // since it can be edited easily by any text editor for testing.
     char data = clean? '1' : '0';
     int32_t filePos = PR_Seek(mCleanFD, 0, PR_SEEK_SET);
     if (filePos != 0) {
         NS_WARNING("Could not seek in cache clean file!");
         return NS_ERROR_FAILURE;
     }
     int32_t bytesWritten = PR_Write(mCleanFD, &data, 1);
     if (bytesWritten != 1) {
         NS_WARNING("Could not write cache clean file!");
         return NS_ERROR_FAILURE;
     }
     PRStatus err = PR_Sync(mCleanFD);
     if (err != PR_SUCCESS) {
         NS_WARNING("Could not flush cache clean file!");
     }
     return NS_OK;
 }
 nsresult
 nsDiskCacheMap::InvalidateCache()
 {
     nsCacheService::AssertOwnsLock();
     CACHE_LOG_DEBUG(("CACHE: InvalidateCache\n"));
     nsresult rv;
     if (!mIsDirtyCacheFlushed) {
         rv = WriteCacheClean(false);
         if (NS_FAILED(rv)) {
           Telemetry::Accumulate(Telemetry::DISK_CACHE_INVALIDATION_SUCCESS, 0);
           return rv;
         }
         Telemetry::Accumulate(Telemetry::DISK_CACHE_INVALIDATION_SUCCESS, 1);
         mIsDirtyCacheFlushed = true;
     }
     rv = ResetCacheTimer();
     NS_ENSURE_SUCCESS(rv, rv);
     return NS_OK;
 }
 nsresult
 nsDiskCacheMap::ResetCacheTimer(int32_t timeout)
 {
     mCleanCacheTimer->Cancel();
     nsresult rv =
       mCleanCacheTimer->InitWithFuncCallback(RevalidateTimerCallback,
                                              nullptr, timeout,
                                              nsITimer::TYPE_ONE_SHOT);
     NS_ENSURE_SUCCESS(rv, rv);
     mLastInvalidateTime = PR_IntervalNow();
     return rv;
 }
 void
 nsDiskCacheMap::RevalidateTimerCallback(nsITimer *aTimer, void *arg)
 {
     nsCacheServiceAutoLock lock(LOCK_TELEM(NSDISKCACHEMAP_REVALIDATION));
     if (!nsCacheService::gService->mDiskDevice ||
         !nsCacheService::gService->mDiskDevice->Initialized()) {
         return;
     }
     nsDiskCacheMap *diskCacheMap =
         &nsCacheService::gService->mDiskDevice->mCacheMap;
     // If we have less than kRevalidateCacheTimeout since the last timer was
     // issued then another thread called InvalidateCache.  This won't catch
     // all cases where we wanted to cancel the timer, but under the lock it
     // is always OK to revalidate as long as IsCacheInSafeState() returns
     // true.  We just want to avoid revalidating when we can to reduce IO
     // and this check will do that.
     uint32_t delta =
         PR_IntervalToMilliseconds(PR_IntervalNow() -
                                   diskCacheMap->mLastInvalidateTime) +
         kRevalidateCacheTimeoutTolerance;
     if (delta < kRevalidateCacheTimeout) {
         diskCacheMap->ResetCacheTimer();
         return;
     }
     nsresult rv = diskCacheMap->RevalidateCache();
     if (NS_FAILED(rv)) {
         diskCacheMap->ResetCacheTimer(kRevalidateCacheErrorTimeout);
     }
 }
 bool
 nsDiskCacheMap::IsCacheInSafeState()
 {
     return nsCacheService::GlobalInstance()->IsDoomListEmpty();
 }
 nsresult
 nsDiskCacheMap::RevalidateCache()
 {
     CACHE_LOG_DEBUG(("CACHE: RevalidateCache\n"));
     nsresult rv;
     if (!IsCacheInSafeState()) {
         Telemetry::Accumulate(Telemetry::DISK_CACHE_REVALIDATION_SAFE, 0);
         CACHE_LOG_DEBUG(("CACHE: Revalidation should not performed because "
                          "cache not in a safe state\n"));
         // Normally we would return an error here, but there is a bug where
         // the doom list sometimes gets an entry 'stuck' and doens't clear it
         // until browser shutdown.  So we allow revalidation for the time being
         // to get proper telemetry data of how much the cache corruption plan
         // would help.
     } else {
         Telemetry::Accumulate(Telemetry::DISK_CACHE_REVALIDATION_SAFE, 1);
     }
     // We want this after the lock to prove that flushing a file isn't that expensive
     Telemetry::AutoTimer<Telemetry::NETWORK_DISK_CACHE_REVALIDATION> totalTimer;
     // If telemetry data shows it is worth it, we'll be flushing headers and
     // records before flushing the clean cache file.
     // Write out the _CACHE_CLEAN_ file with '1'
     rv = WriteCacheClean(true);
     if (NS_FAILED(rv)) {
         Telemetry::Accumulate(Telemetry::DISK_CACHE_REVALIDATION_SUCCESS, 0);
         return rv;
     }
     Telemetry::Accumulate(Telemetry::DISK_CACHE_REVALIDATION_SUCCESS, 1);
     mIsDirtyCacheFlushed = false;
     return NS_OK;
 }

The Tor Browser / annotate

netwerk/cache/nsDiskCacheMap.cpp@b8a032363ba2 (annotated)

netwerk/cache/nsDiskCacheMap.cpp