The Tor Browser: ipc/chromium/src/base/tracked_objects.h@6474c204b198 (annotated)

ipc/chromium/src/base/tracked_objects.h@6474c204b198 (annotated)

ipc/chromium/src/base/tracked_objects.h

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 #ifndef BASE_TRACKED_OBJECTS_H_
 #define BASE_TRACKED_OBJECTS_H_
 //------------------------------------------------------------------------------
 #include <map>
 #include <string>
 #include <vector>
 #include "base/lock.h"
 #include "base/message_loop.h"
 #include "base/thread_local_storage.h"
 #include "base/tracked.h"
 namespace tracked_objects {
 //------------------------------------------------------------------------------
 // For a specific thread, and a specific birth place, the collection of all
 // death info (with tallies for each death thread, to prevent access conflicts).
 class ThreadData;
 class BirthOnThread {
  public:
   explicit BirthOnThread(const Location& location);
   const Location location() const { return location_; }
   const ThreadData* birth_thread() const { return birth_thread_; }
  private:
   // File/lineno of birth.  This defines the essence of the type, as the context
   // of the birth (construction) often tell what the item is for.  This field
   // is const, and hence safe to access from any thread.
   const Location location_;
   // The thread that records births into this object.  Only this thread is
   // allowed to access birth_count_ (which changes over time).
   const ThreadData* birth_thread_;  // The thread this birth took place on.
   DISALLOW_COPY_AND_ASSIGN(BirthOnThread);
 };
 //------------------------------------------------------------------------------
 // A class for accumulating counts of births (without bothering with a map<>).
 class Births: public BirthOnThread {
  public:
   explicit Births(const Location& location);
   int birth_count() const { return birth_count_; }
   // When we have a birth we update the count for this BirhPLace.
   void RecordBirth() { ++birth_count_; }
   // When a birthplace is changed (updated), we need to decrement the counter
   // for the old instance.
   void ForgetBirth() { --birth_count_; }  // We corrected a birth place.
  private:
   // The number of births on this thread for our location_.
   int birth_count_;
   DISALLOW_COPY_AND_ASSIGN(Births);
 };
 //------------------------------------------------------------------------------
 // Basic info summarizing multiple destructions of an object with a single
 // birthplace (fixed Location).  Used both on specific threads, and also used
 // in snapshots when integrating assembled data.
 class DeathData {
  public:
   // Default initializer.
   DeathData() : count_(0), square_duration_(0) {}
   // When deaths have not yet taken place, and we gather data from all the
   // threads, we create DeathData stats that tally the number of births without
   // a corrosponding death.
   explicit DeathData(int count) : count_(count), square_duration_(0) {}
   void RecordDeath(const base::TimeDelta& duration);
   // Metrics accessors.
   int count() const { return count_; }
   base::TimeDelta life_duration() const { return life_duration_; }
   int64_t square_duration() const { return square_duration_; }
   int AverageMsDuration() const;
   double StandardDeviation() const;
   // Accumulate metrics from other into this.
   void AddDeathData(const DeathData& other);
   // Simple print of internal state.
   void Write(std::string* output) const;
   void Clear();
  private:
   int count_;                // Number of destructions.
   base::TimeDelta life_duration_;    // Sum of all lifetime durations.
   int64_t square_duration_;  // Sum of squares in milliseconds.
 };
 //------------------------------------------------------------------------------
 // A temporary collection of data that can be sorted and summarized.  It is
 // gathered (carefully) from many threads.  Instances are held in arrays and
 // processed, filtered, and rendered.
 // The source of this data was collected on many threads, and is asynchronously
 // changing.  The data in this instance is not asynchronously changing.
 class Snapshot {
  public:
   // When snapshotting a full life cycle set (birth-to-death), use this:
   Snapshot(const BirthOnThread& birth_on_thread, const ThreadData& death_thread,
            const DeathData& death_data);
   // When snapshotting a birth, with no death yet, use this:
   Snapshot(const BirthOnThread& birth_on_thread, int count);
   const ThreadData* birth_thread() const { return birth_->birth_thread(); }
   const Location location() const { return birth_->location(); }
   const BirthOnThread& birth() const { return *birth_; }
   const ThreadData* death_thread() const {return death_thread_; }
   const DeathData& death_data() const { return death_data_; }
   const std::string DeathThreadName() const;
   int count() const { return death_data_.count(); }
   base::TimeDelta life_duration() const { return death_data_.life_duration(); }
   int64_t square_duration() const { return death_data_.square_duration(); }
   int AverageMsDuration() const { return death_data_.AverageMsDuration(); }
   void Write(std::string* output) const;
   void Add(const Snapshot& other);
  private:
   const BirthOnThread* birth_;  // Includes Location and birth_thread.
   const ThreadData* death_thread_;
   DeathData death_data_;
 };
 //------------------------------------------------------------------------------
 // DataCollector is a container class for Snapshot and BirthOnThread count
 // items.  It protects the gathering under locks, so that it could be called via
 // Posttask on any threads, such as all the target threads in parallel.
 class DataCollector {
  public:
   typedef std::vector<Snapshot> Collection;
   // Construct with a list of how many threads should contribute.  This helps us
   // determine (in the async case) when we are done with all contributions.
   DataCollector();
   // Add all stats from the indicated thread into our arrays.  This function is
   // mutex protected, and *could* be called from any threads (although current
   // implementation serialized calls to Append).
   void Append(const ThreadData& thread_data);
   // After the accumulation phase, the following access is to process data.
   Collection* collection();
   // After collection of death data is complete, we can add entries for all the
   // remaining living objects.
   void AddListOfLivingObjects();
  private:
   // This instance may be provided to several threads to contribute data.  The
   // following counter tracks how many more threads will contribute.  When it is
   // zero, then all asynchronous contributions are complete, and locked access
   // is no longer needed.
   int count_of_contributing_threads_;
   // The array that we collect data into.
   Collection collection_;
   // The total number of births recorded at each location for which we have not
   // seen a death count.
   typedef std::map<const BirthOnThread*, int> BirthCount;
   BirthCount global_birth_count_;
   Lock accumulation_lock_;  // Protects access during accumulation phase.
   DISALLOW_COPY_AND_ASSIGN(DataCollector);
 };
 //------------------------------------------------------------------------------
 // Aggregation contains summaries (totals and subtotals) of groups of Snapshot
 // instances to provide printing of these collections on a single line.
 class Aggregation: public DeathData {
  public:
   Aggregation() : birth_count_(0) {}
   void AddDeathSnapshot(const Snapshot& snapshot);
   void AddBirths(const Births& births);
   void AddBirth(const BirthOnThread& birth);
   void AddBirthPlace(const Location& location);
   void Write(std::string* output) const;
   void Clear();
  private:
   int birth_count_;
   std::map<std::string, int> birth_files_;
   std::map<Location, int> locations_;
   std::map<const ThreadData*, int> birth_threads_;
   DeathData death_data_;
   std::map<const ThreadData*, int> death_threads_;
   DISALLOW_COPY_AND_ASSIGN(Aggregation);
 };
 //------------------------------------------------------------------------------
 // Comparator does the comparison of Snapshot instances.  It is
 // used to order the instances in a vector.  It orders them into groups (for
 // aggregation), and can also order instances within the groups (for detailed
 // rendering of the instances).
 class Comparator {
  public:
   enum Selector {
     NIL = 0,
     BIRTH_THREAD = 1,
     DEATH_THREAD = 2,
     BIRTH_FILE = 4,
     BIRTH_FUNCTION = 8,
     BIRTH_LINE = 16,
     COUNT = 32,
     AVERAGE_DURATION = 64,
     TOTAL_DURATION = 128
   };
   explicit Comparator();
   // Reset the comparator to a NIL selector.  Reset() and recursively delete any
   // tiebreaker_ entries.  NOTE: We can't use a standard destructor, because
   // the sort algorithm makes copies of this object, and then deletes them,
   // which would cause problems (either we'd make expensive deep copies, or we'd
   // do more thna one delete on a tiebreaker_.
   void Clear();
   // The less() operator for sorting the array via std::sort().
   bool operator()(const Snapshot& left, const Snapshot& right) const;
   void Sort(DataCollector::Collection* collection) const;
   // Check to see if the items are sort equivalents (should be aggregated).
   bool Equivalent(const Snapshot& left, const Snapshot& right) const;
   // Check to see if all required fields are present in the given sample.
   bool Acceptable(const Snapshot& sample) const;
   // A comparator can be refined by specifying what to do if the selected basis
   // for comparison is insufficient to establish an ordering.  This call adds
   // the indicated attribute as the new "least significant" basis of comparison.
   void SetTiebreaker(Selector selector, const std::string required);
   // Indicate if this instance is set up to sort by the given Selector, thereby
   // putting that information in the SortGrouping, so it is not needed in each
   // printed line.
   bool IsGroupedBy(Selector selector) const;
   // Using the tiebreakers as set above, we mostly get an ordering, which
   // equivalent groups.  If those groups are displayed (rather than just being
   // aggregated, then the following is used to order them (within the group).
   void SetSubgroupTiebreaker(Selector selector);
   // Output a header line that can be used to indicated what items will be
   // collected in the group.  It lists all (potentially) tested attributes and
   // their values (in the sample item).
   bool WriteSortGrouping(const Snapshot& sample, std::string* output) const;
   // Output a sample, with SortGroup details not displayed.
   void WriteSnapshot(const Snapshot& sample, std::string* output) const;
  private:
   // The selector directs this instance to compare based on the specified
   // members of the tested elements.
   enum Selector selector_;
   // For filtering into acceptable and unacceptable snapshot instance, the
   // following is required to be a substring of the selector_ field.
   std::string required_;
   // If this instance can't decide on an ordering, we can consult a tie-breaker
   // which may have a different basis of comparison.
   Comparator* tiebreaker_;
   // We or together all the selectors we sort on (not counting sub-group
   // selectors), so that we can tell if we've decided to group on any given
   // criteria.
   int combined_selectors_;
   // Some tiebreakrs are for subgroup ordering, and not for basic ordering (in
   // preparation for aggregation).  The subgroup tiebreakers are not consulted
   // when deciding if two items are in equivalent groups.  This flag tells us
   // to ignore the tiebreaker when doing Equivalent() testing.
   bool use_tiebreaker_for_sort_only_;
 };
 //------------------------------------------------------------------------------
 // For each thread, we have a ThreadData that stores all tracking info generated
 // on this thread.  This prevents the need for locking as data accumulates.
 class ThreadData {
  public:
   typedef std::map<Location, Births*> BirthMap;
   typedef std::map<const Births*, DeathData> DeathMap;
   ThreadData();
   // Using Thread Local Store, find the current instance for collecting data.
   // If an instance does not exist, construct one (and remember it for use on
   // this thread.
   // If shutdown has already started, and we don't yet have an instance, then
   // return null.
   static ThreadData* current();
   // In this thread's data, find a place to record a new birth.
   Births* FindLifetime(const Location& location);
   // Find a place to record a death on this thread.
   void TallyADeath(const Births& lifetimes, const base::TimeDelta& duration);
   // (Thread safe) Get start of list of instances.
   static ThreadData* first();
   // Iterate through the null terminated list of instances.
   ThreadData* next() const { return next_; }
   MessageLoop* message_loop() const { return message_loop_; }
   const std::string ThreadName() const;
   // Using our lock, make a copy of the specified maps.  These calls may arrive
   // from non-local threads.
   void SnapshotBirthMap(BirthMap *output) const;
   void SnapshotDeathMap(DeathMap *output) const;
   static void RunOnAllThreads(void (*Func)());
   // Set internal status_ to either become ACTIVE, or later, to be SHUTDOWN,
   // based on argument being true or false respectively.
   // IF tracking is not compiled in, this function will return false.
   static bool StartTracking(bool status);
   static bool IsActive();
 #ifdef OS_WIN
   // WARNING: ONLY call this function when all MessageLoops are still intact for
   // all registered threads.  IF you call it later, you will crash.
   // Note: You don't need to call it at all, and you can wait till you are
   // single threaded (again) to do the cleanup via
   // ShutdownSingleThreadedCleanup().
   // Start the teardown (shutdown) process in a multi-thread mode by disabling
   // further additions to thread database on all threads.  First it makes a
   // local (locked) change to prevent any more threads from registering.  Then
   // it Posts a Task to all registered threads to be sure they are aware that no
   // more accumulation can take place.
   static void ShutdownMultiThreadTracking();
 #endif
   // WARNING: ONLY call this function when you are running single threaded
   // (again) and all message loops and threads have terminated.  Until that
   // point some threads may still attempt to write into our data structures.
   // Delete recursively all data structures, starting with the list of
   // ThreadData instances.
   static void ShutdownSingleThreadedCleanup();
  private:
   // Current allowable states of the tracking system.  The states always
   // proceed towards SHUTDOWN, and never go backwards.
   enum Status {
     UNINITIALIZED,
     ACTIVE,
     SHUTDOWN
   };
   // A class used to count down which is accessed by several threads.  This is
   // used to make sure RunOnAllThreads() actually runs a task on the expected
   // count of threads.
   class ThreadSafeDownCounter {
    public:
     // Constructor sets the count, once and for all.
     explicit ThreadSafeDownCounter(size_t count);
     // Decrement the count, and return true if we hit zero.  Also delete this
     // instance automatically when we hit zero.
     bool LastCaller();
    private:
     size_t remaining_count_;
     Lock lock_;  // protect access to remaining_count_.
   };
 #ifdef OS_WIN
   // A Task class that runs a static method supplied, and checks to see if this
   // is the last tasks instance (on last thread) that will run the method.
   // IF this is the last run, then the supplied event is signalled.
   class RunTheStatic : public Task {
    public:
     typedef void (*FunctionPointer)();
     RunTheStatic(FunctionPointer function,
                  HANDLE completion_handle,
                  ThreadSafeDownCounter* counter);
     // Run the supplied static method, and optionally set the event.
     void Run();
    private:
     FunctionPointer function_;
     HANDLE completion_handle_;
     // Make sure enough tasks are called before completion is signaled.
     ThreadSafeDownCounter* counter_;
     DISALLOW_COPY_AND_ASSIGN(RunTheStatic);
   };
 #endif
   // Each registered thread is called to set status_ to SHUTDOWN.
   // This is done redundantly on every registered thread because it is not
   // protected by a mutex.  Running on all threads guarantees we get the
   // notification into the memory cache of all possible threads.
   static void ShutdownDisablingFurtherTracking();
   // We use thread local store to identify which ThreadData to interact with.
   static TLSSlot tls_index_ ;
   // Link to the most recently created instance (starts a null terminated list).
   static ThreadData* first_;
   // Protection for access to first_.
   static Lock list_lock_;
   // We set status_ to SHUTDOWN when we shut down the tracking service. This
   // setting is redundantly established by all participating
   // threads so that we are *guaranteed* (without locking) that all threads
   // can "see" the status and avoid additional calls into the  service.
   static Status status_;
   // Link to next instance (null terminated list). Used to globally track all
   // registered instances (corresponds to all registered threads where we keep
   // data).
   ThreadData* next_;
   // The message loop where tasks needing to access this instance's private data
   // should be directed.  Since some threads have no message loop, some
   // instances have data that can't be (safely) modified externally.
   MessageLoop* message_loop_;
   // A map used on each thread to keep track of Births on this thread.
   // This map should only be accessed on the thread it was constructed on.
   // When a snapshot is needed, this structure can be locked in place for the
   // duration of the snapshotting activity.
   BirthMap birth_map_;
   // Similar to birth_map_, this records informations about death of tracked
   // instances (i.e., when a tracked instance was destroyed on this thread).
   DeathMap death_map_;
   // Lock to protect *some* access to BirthMap and DeathMap.  We only use
   // locking protection when we are growing the maps, or using an iterator.  We
   // only do writes to members from this thread, so the updates of values are
   // atomic.  Folks can read from other threads, and get (via races) new or old
   // data, but that is considered acceptable errors (mis-information).
   Lock lock_;
   DISALLOW_COPY_AND_ASSIGN(ThreadData);
 };
 //------------------------------------------------------------------------------
 // Provide simple way to to start global tracking, and to tear down tracking
 // when done.  Note that construction and destruction of this object must be
 // done when running in single threaded mode (before spawning a lot of threads
 // for construction, and after shutting down all the threads for destruction).
 class AutoTracking {
  public:
   AutoTracking() { ThreadData::StartTracking(true); }
   ~AutoTracking() {
 #ifndef NDEBUG  // Don't call these in a Release build: they just waste time.
     // The following should ONLY be called when in single threaded mode. It is
     // unsafe to do this cleanup if other threads are still active.
     // It is also very unnecessary, so I'm only doing this in debug to satisfy
     // purify (if we need to!).
     ThreadData::ShutdownSingleThreadedCleanup();
 #endif
   }
  private:
   DISALLOW_COPY_AND_ASSIGN(AutoTracking);
 };
 }  // namespace tracked_objects
 #endif  // BASE_TRACKED_OBJECTS_H_

The Tor Browser / annotate

ipc/chromium/src/base/tracked_objects.h@6474c204b198 (annotated)

ipc/chromium/src/base/tracked_objects.h