The Tor Browser: dom/system/gonk/worker_buf.js@6474c204b198 (annotated)

dom/system/gonk/worker_buf.js@6474c204b198 (annotated)

dom/system/gonk/worker_buf.js

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.

 /* 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/. */
 /**
  * This object contains helpers buffering incoming data & deconstructing it
  * into parcels as well as buffering outgoing data & constructing parcels.
  * For that it maintains two buffers and corresponding uint8 views, indexes.
  *
  * The incoming buffer is a circular buffer where we store incoming data.
  * As soon as a complete parcel is received, it is processed right away, so
  * the buffer only needs to be large enough to hold one parcel.
  *
  * The outgoing buffer is to prepare outgoing parcels. The index is reset
  * every time a parcel is sent.
  */
 let Buf = {
   INT32_MAX: 2147483647,
   UINT8_SIZE: 1,
   UINT16_SIZE: 2,
   UINT32_SIZE: 4,
   PARCEL_SIZE_SIZE: 4,
   PDU_HEX_OCTET_SIZE: 4,
   incomingBufferLength: 1024,
   incomingBuffer: null,
   incomingBytes: null,
   incomingWriteIndex: 0,
   incomingReadIndex: 0,
   readIncoming: 0,
   readAvailable: 0,
   currentParcelSize: 0,
   outgoingBufferLength: 1024,
   outgoingBuffer: null,
   outgoingBytes: null,
   outgoingIndex: 0,
   outgoingBufferCalSizeQueue: null,
   _init: function() {
     this.incomingBuffer = new ArrayBuffer(this.incomingBufferLength);
     this.outgoingBuffer = new ArrayBuffer(this.outgoingBufferLength);
     this.incomingBytes = new Uint8Array(this.incomingBuffer);
     this.outgoingBytes = new Uint8Array(this.outgoingBuffer);
     // Track where incoming data is read from and written to.
     this.incomingWriteIndex = 0;
     this.incomingReadIndex = 0;
     // Leave room for the parcel size for outgoing parcels.
     this.outgoingIndex = this.PARCEL_SIZE_SIZE;
     // How many bytes we've read for this parcel so far.
     this.readIncoming = 0;
     // How many bytes available as parcel data.
     this.readAvailable = 0;
     // Size of the incoming parcel. If this is zero, we're expecting a new
     // parcel.
     this.currentParcelSize = 0;
     // Queue for storing outgoing override points
     this.outgoingBufferCalSizeQueue = [];
   },
   /**
    * Mark current outgoingIndex as start point for calculation length of data
    * written to outgoingBuffer.
    * Mark can be nested for here uses queue to remember marks.
    *
    * @param writeFunction
    *        Function to write data length into outgoingBuffer, this function is
    *        also used to allocate buffer for data length.
    *        Raw data size(in Uint8) is provided as parameter calling writeFunction.
    *        If raw data size is not in proper unit for writing, user can adjust
    *        the length value in writeFunction before writing.
    **/
   startCalOutgoingSize: function(writeFunction) {
     let sizeInfo = {index: this.outgoingIndex,
                     write: writeFunction};
     // Allocate buffer for data lemgtj.
     writeFunction.call(0);
     // Get size of data length buffer for it is not counted into data size.
     sizeInfo.size = this.outgoingIndex - sizeInfo.index;
     // Enqueue size calculation information.
     this.outgoingBufferCalSizeQueue.push(sizeInfo);
   },
   /**
    * Calculate data length since last mark, and write it into mark position.
    **/
   stopCalOutgoingSize: function() {
     let sizeInfo = this.outgoingBufferCalSizeQueue.pop();
     // Remember current outgoingIndex.
     let currentOutgoingIndex = this.outgoingIndex;
     // Calculate data length, in uint8.
     let writeSize = this.outgoingIndex - sizeInfo.index - sizeInfo.size;
     // Write data length to mark, use same function for allocating buffer to make
     // sure there is no buffer overloading.
     this.outgoingIndex = sizeInfo.index;
     sizeInfo.write(writeSize);
     // Restore outgoingIndex.
     this.outgoingIndex = currentOutgoingIndex;
   },
   /**
    * Grow the incoming buffer.
    *
    * @param min_size
    *        Minimum new size. The actual new size will be the the smallest
    *        power of 2 that's larger than this number.
    */
   growIncomingBuffer: function(min_size) {
     if (DEBUG) {
       debug("Current buffer of " + this.incomingBufferLength +
             " can't handle incoming " + min_size + " bytes.");
     }
     let oldBytes = this.incomingBytes;
     this.incomingBufferLength =
 << Math.floor(Math.log(min_size)/Math.log(2));
     if (DEBUG) debug("New incoming buffer size: " + this.incomingBufferLength);
     this.incomingBuffer = new ArrayBuffer(this.incomingBufferLength);
     this.incomingBytes = new Uint8Array(this.incomingBuffer);
     if (this.incomingReadIndex <= this.incomingWriteIndex) {
       // Read and write index are in natural order, so we can just copy
       // the old buffer over to the bigger one without having to worry
       // about the indexes.
       this.incomingBytes.set(oldBytes, 0);
     } else {
       // The write index has wrapped around but the read index hasn't yet.
       // Write whatever the read index has left to read until it would
       // circle around to the beginning of the new buffer, and the rest
       // behind that.
       let head = oldBytes.subarray(this.incomingReadIndex);
       let tail = oldBytes.subarray(0, this.incomingReadIndex);
       this.incomingBytes.set(head, 0);
       this.incomingBytes.set(tail, head.length);
       this.incomingReadIndex = 0;
       this.incomingWriteIndex += head.length;
     }
     if (DEBUG) {
       debug("New incoming buffer size is " + this.incomingBufferLength);
     }
   },
   /**
    * Grow the outgoing buffer.
    *
    * @param min_size
    *        Minimum new size. The actual new size will be the the smallest
    *        power of 2 that's larger than this number.
    */
   growOutgoingBuffer: function(min_size) {
     if (DEBUG) {
       debug("Current buffer of " + this.outgoingBufferLength +
             " is too small.");
     }
     let oldBytes = this.outgoingBytes;
     this.outgoingBufferLength =
 << Math.floor(Math.log(min_size)/Math.log(2));
     this.outgoingBuffer = new ArrayBuffer(this.outgoingBufferLength);
     this.outgoingBytes = new Uint8Array(this.outgoingBuffer);
     this.outgoingBytes.set(oldBytes, 0);
     if (DEBUG) {
       debug("New outgoing buffer size is " + this.outgoingBufferLength);
     }
   },
   /**
    * Functions for reading data from the incoming buffer.
    *
    * These are all little endian, apart from readParcelSize();
    */
   /**
    * Ensure position specified is readable.
    *
    * @param index
    *        Data position in incoming parcel, valid from 0 to
    *        currentParcelSize.
    */
   ensureIncomingAvailable: function(index) {
     if (index >= this.currentParcelSize) {
       throw new Error("Trying to read data beyond the parcel end!");
     } else if (index < 0) {
       throw new Error("Trying to read data before the parcel begin!");
     }
   },
   /**
    * Seek in current incoming parcel.
    *
    * @param offset
    *        Seek offset in relative to current position.
    */
   seekIncoming: function(offset) {
     // Translate to 0..currentParcelSize
     let cur = this.currentParcelSize - this.readAvailable;
     let newIndex = cur + offset;
     this.ensureIncomingAvailable(newIndex);
     // ... incomingReadIndex -->|
     // 0               new     cur           currentParcelSize
     // |================|=======|====================|
     // |<--        cur       -->|<- readAvailable ->|
     // |<-- newIndex -->|<--  new readAvailable  -->|
     this.readAvailable = this.currentParcelSize - newIndex;
     // Translate back:
     if (this.incomingReadIndex < cur) {
       // The incomingReadIndex is wrapped.
       newIndex += this.incomingBufferLength;
     }
     newIndex += (this.incomingReadIndex - cur);
     newIndex %= this.incomingBufferLength;
     this.incomingReadIndex = newIndex;
   },
   readUint8Unchecked: function() {
     let value = this.incomingBytes[this.incomingReadIndex];
     this.incomingReadIndex = (this.incomingReadIndex + 1) %
                              this.incomingBufferLength;
     return value;
   },
   readUint8: function() {
     // Translate to 0..currentParcelSize
     let cur = this.currentParcelSize - this.readAvailable;
     this.ensureIncomingAvailable(cur);
     this.readAvailable--;
     return this.readUint8Unchecked();
   },
   readUint8Array: function(length) {
     // Translate to 0..currentParcelSize
     let last = this.currentParcelSize - this.readAvailable;
     last += (length - 1);
     this.ensureIncomingAvailable(last);
     let array = new Uint8Array(length);
     for (let i = 0; i < length; i++) {
       array[i] = this.readUint8Unchecked();
     }
     this.readAvailable -= length;
     return array;
   },
   readUint16: function() {
     return this.readUint8() | this.readUint8() << 8;
   },
   readInt32: function() {
     return this.readUint8()       | this.readUint8() <<  8 |
            this.readUint8() << 16 | this.readUint8() << 24;
   },
   readInt32List: function() {
     let length = this.readInt32();
     let ints = [];
     for (let i = 0; i < length; i++) {
       ints.push(this.readInt32());
     }
     return ints;
   },
   readString: function() {
     let string_len = this.readInt32();
     if (string_len < 0 || string_len >= this.INT32_MAX) {
       return null;
     }
     let s = "";
     for (let i = 0; i < string_len; i++) {
       s += String.fromCharCode(this.readUint16());
     }
     // Strings are \0\0 delimited, but that isn't part of the length. And
     // if the string length is even, the delimiter is two characters wide.
     // It's insane, I know.
     this.readStringDelimiter(string_len);
     return s;
   },
   readStringList: function() {
     let num_strings = this.readInt32();
     let strings = [];
     for (let i = 0; i < num_strings; i++) {
       strings.push(this.readString());
     }
     return strings;
   },
   readStringDelimiter: function(length) {
     let delimiter = this.readUint16();
     if (!(length & 1)) {
       delimiter |= this.readUint16();
     }
     if (DEBUG) {
       if (delimiter !== 0) {
         debug("Something's wrong, found string delimiter: " + delimiter);
       }
     }
   },
   readParcelSize: function() {
     return this.readUint8Unchecked() << 24 |
            this.readUint8Unchecked() << 16 |
            this.readUint8Unchecked() <<  8 |
            this.readUint8Unchecked();
   },
   /**
    * Functions for writing data to the outgoing buffer.
    */
   /**
    * Ensure position specified is writable.
    *
    * @param index
    *        Data position in outgoing parcel, valid from 0 to
    *        outgoingBufferLength.
    */
   ensureOutgoingAvailable: function(index) {
     if (index >= this.outgoingBufferLength) {
       this.growOutgoingBuffer(index + 1);
     }
   },
   writeUint8: function(value) {
     this.ensureOutgoingAvailable(this.outgoingIndex);
     this.outgoingBytes[this.outgoingIndex] = value;
     this.outgoingIndex++;
   },
   writeUint16: function(value) {
     this.writeUint8(value & 0xff);
     this.writeUint8((value >> 8) & 0xff);
   },
   writeInt32: function(value) {
     this.writeUint8(value & 0xff);
     this.writeUint8((value >> 8) & 0xff);
     this.writeUint8((value >> 16) & 0xff);
     this.writeUint8((value >> 24) & 0xff);
   },
   writeString: function(value) {
     if (value == null) {
       this.writeInt32(-1);
       return;
     }
     this.writeInt32(value.length);
     for (let i = 0; i < value.length; i++) {
       this.writeUint16(value.charCodeAt(i));
     }
     // Strings are \0\0 delimited, but that isn't part of the length. And
     // if the string length is even, the delimiter is two characters wide.
     // It's insane, I know.
     this.writeStringDelimiter(value.length);
   },
   writeStringList: function(strings) {
     this.writeInt32(strings.length);
     for (let i = 0; i < strings.length; i++) {
       this.writeString(strings[i]);
     }
   },
   writeStringDelimiter: function(length) {
     this.writeUint16(0);
     if (!(length & 1)) {
       this.writeUint16(0);
     }
   },
   writeParcelSize: function(value) {
     /**
      *  Parcel size will always be the first thing in the parcel byte
      *  array, but the last thing written. Store the current index off
      *  to a temporary to be reset after we write the size.
      */
     let currentIndex = this.outgoingIndex;
     this.outgoingIndex = 0;
     this.writeUint8((value >> 24) & 0xff);
     this.writeUint8((value >> 16) & 0xff);
     this.writeUint8((value >> 8) & 0xff);
     this.writeUint8(value & 0xff);
     this.outgoingIndex = currentIndex;
   },
   copyIncomingToOutgoing: function(length) {
     if (!length || (length < 0)) {
       return;
     }
     let translatedReadIndexEnd =
       this.currentParcelSize - this.readAvailable + length - 1;
     this.ensureIncomingAvailable(translatedReadIndexEnd);
     let translatedWriteIndexEnd = this.outgoingIndex + length - 1;
     this.ensureOutgoingAvailable(translatedWriteIndexEnd);
     let newIncomingReadIndex = this.incomingReadIndex + length;
     if (newIncomingReadIndex < this.incomingBufferLength) {
       // Reading won't cause wrapping, go ahead with builtin copy.
       this.outgoingBytes
           .set(this.incomingBytes.subarray(this.incomingReadIndex,
                                            newIncomingReadIndex),
                this.outgoingIndex);
     } else {
       // Not so lucky.
       newIncomingReadIndex %= this.incomingBufferLength;
       this.outgoingBytes
           .set(this.incomingBytes.subarray(this.incomingReadIndex,
                                            this.incomingBufferLength),
                this.outgoingIndex);
       if (newIncomingReadIndex) {
         let firstPartLength = this.incomingBufferLength - this.incomingReadIndex;
         this.outgoingBytes.set(this.incomingBytes.subarray(0, newIncomingReadIndex),
                                this.outgoingIndex + firstPartLength);
       }
     }
     this.incomingReadIndex = newIncomingReadIndex;
     this.readAvailable -= length;
     this.outgoingIndex += length;
   },
   /**
    * Parcel management
    */
   /**
    * Write incoming data to the circular buffer.
    *
    * @param incoming
    *        Uint8Array containing the incoming data.
    */
   writeToIncoming: function(incoming) {
     // We don't have to worry about the head catching the tail since
     // we process any backlog in parcels immediately, before writing
     // new data to the buffer. So the only edge case we need to handle
     // is when the incoming data is larger than the buffer size.
     let minMustAvailableSize = incoming.length + this.readIncoming;
     if (minMustAvailableSize > this.incomingBufferLength) {
       this.growIncomingBuffer(minMustAvailableSize);
     }
     // We can let the typed arrays do the copying if the incoming data won't
     // wrap around the edges of the circular buffer.
     let remaining = this.incomingBufferLength - this.incomingWriteIndex;
     if (remaining >= incoming.length) {
       this.incomingBytes.set(incoming, this.incomingWriteIndex);
     } else {
       // The incoming data would wrap around it.
       let head = incoming.subarray(0, remaining);
       let tail = incoming.subarray(remaining);
       this.incomingBytes.set(head, this.incomingWriteIndex);
       this.incomingBytes.set(tail, 0);
     }
     this.incomingWriteIndex = (this.incomingWriteIndex + incoming.length) %
                                this.incomingBufferLength;
   },
   /**
    * Process incoming data.
    *
    * @param incoming
    *        Uint8Array containing the incoming data.
    */
   processIncoming: function(incoming) {
     if (DEBUG) {
       debug("Received " + incoming.length + " bytes.");
       debug("Already read " + this.readIncoming);
     }
     this.writeToIncoming(incoming);
     this.readIncoming += incoming.length;
     while (true) {
       if (!this.currentParcelSize) {
         // We're expecting a new parcel.
         if (this.readIncoming < this.PARCEL_SIZE_SIZE) {
           // We don't know how big the next parcel is going to be, need more
           // data.
           if (DEBUG) debug("Next parcel size unknown, going to sleep.");
           return;
         }
         this.currentParcelSize = this.readParcelSize();
         if (DEBUG) {
           debug("New incoming parcel of size " + this.currentParcelSize);
         }
         // The size itself is not included in the size.
         this.readIncoming -= this.PARCEL_SIZE_SIZE;
       }
       if (this.readIncoming < this.currentParcelSize) {
         // We haven't read enough yet in order to be able to process a parcel.
         if (DEBUG) debug("Read " + this.readIncoming + ", but parcel size is "
                          + this.currentParcelSize + ". Going to sleep.");
         return;
       }
       // Alright, we have enough data to process at least one whole parcel.
       // Let's do that.
       let expectedAfterIndex = (this.incomingReadIndex + this.currentParcelSize)
                                % this.incomingBufferLength;
       if (DEBUG) {
         let parcel;
         if (expectedAfterIndex < this.incomingReadIndex) {
           let head = this.incomingBytes.subarray(this.incomingReadIndex);
           let tail = this.incomingBytes.subarray(0, expectedAfterIndex);
           parcel = Array.slice(head).concat(Array.slice(tail));
         } else {
           parcel = Array.slice(this.incomingBytes.subarray(
             this.incomingReadIndex, expectedAfterIndex));
         }
         debug("Parcel (size " + this.currentParcelSize + "): " + parcel);
       }
       if (DEBUG) debug("We have at least one complete parcel.");
       try {
         this.readAvailable = this.currentParcelSize;
         this.processParcel();
       } catch (ex) {
         if (DEBUG) debug("Parcel handling threw " + ex + "\n" + ex.stack);
       }
       // Ensure that the whole parcel was consumed.
       if (this.incomingReadIndex != expectedAfterIndex) {
         if (DEBUG) {
           debug("Parcel handler didn't consume whole parcel, " +
                 Math.abs(expectedAfterIndex - this.incomingReadIndex) +
                 " bytes left over");
         }
         this.incomingReadIndex = expectedAfterIndex;
       }
       this.readIncoming -= this.currentParcelSize;
       this.readAvailable = 0;
       this.currentParcelSize = 0;
     }
   },
   /**
    * Communicate with the IPC thread.
    */
   sendParcel: function() {
     // Compute the size of the parcel and write it to the front of the parcel
     // where we left room for it. Note that he parcel size does not include
     // the size itself.
     let parcelSize = this.outgoingIndex - this.PARCEL_SIZE_SIZE;
     this.writeParcelSize(parcelSize);
     // This assumes that postRILMessage will make a copy of the ArrayBufferView
     // right away!
     let parcel = this.outgoingBytes.subarray(0, this.outgoingIndex);
     if (DEBUG) debug("Outgoing parcel: " + Array.slice(parcel));
     this.onSendParcel(parcel);
     this.outgoingIndex = this.PARCEL_SIZE_SIZE;
   },
   getCurrentParcelSize: function() {
     return this.currentParcelSize;
   },
   getReadAvailable: function() {
     return this.readAvailable;
   }
   /**
    * Process one parcel.
    *
    * |processParcel| is an implementation provided incoming parcel processing
    * function invoked when we have received a complete parcel.  Implementation
    * may call multiple read functions to extract data from the incoming buffer.
    */
   //processParcel: function() {
   //  let something = this.readInt32();
   //  ...
   //},
   /**
    * Write raw data out to underlying channel.
    *
    * |onSendParcel| is an implementation provided stream output function
    * invoked when we're really going to write something out.  We assume the
    * data are completely copied to some output buffer in this call and may
    * be destroyed when it's done.
    *
    * @param parcel
    *        An array of numeric octet data.
    */
   //onSendParcel: function(parcel) {
   //  ...
   //}
 };
 module.exports = { Buf: Buf };