The Tor Browser: xpcom/base/nsICycleCollectorListener.idl@b8a032363ba2 (annotated)

xpcom/base/nsICycleCollectorListener.idl@b8a032363ba2 (annotated)

xpcom/base/nsICycleCollectorListener.idl

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

 /* 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 "nsISupports.idl"
 /**
  * Interfaces for observing the cycle collector's work, both from C++ and
  * from JavaScript.
  *
  * If given an object implementing nsICycleCollectorListener, the cycle
  * collector calls that object's methods as it works, describing the
  * objects it visits, the edges it finds, and the conclusions it reaches
  * about which objects are live.
  *
  * Analyzing cycle collection from JS is harder: an nsICycleCollectorListener
  * mustn't mess with the object graph while the cycle collector is trying to
  * figure it out, which means it can't be implemented by JS code: JS can't do
  * much of anything useful within those constraints. Instead, JS code can
  * instantiate @mozilla.org/cycle-collector-logger;1, a C++ class implementing
  * nsICycleCollectorListener that logs the cycle collector's mumblings and then
  * replays them later to an nsICycleCollectorHandler --- which *can* be
  * implemented in JS.
  */
 /**
  * The interface JS code should implement to receive annotations logged by an
  * @mozilla.org/cycle-collector-logger;1 instance. Pass an instance of this to
  * the logger's 'processNext' method.
  *
  * The methods are a subset of those in nsICycleCollectorListener; see the
  * descriptions there.
  */
 [scriptable, uuid(39a8f80e-7eee-4141-b9ef-6e2a7d6e466d)]
 interface nsICycleCollectorHandler : nsISupports
 {
     void noteRefCountedObject(in ACString aAddress,
                               in unsigned long aRefCount,
                               in ACString aObjectDescription);
     void noteGCedObject(in ACString aAddress,
                         in boolean aMarked,
                         in ACString aObjectDescription,
                         in ACString aCompartmentAddress);
     void noteEdge(in ACString aFromAddress,
                   in ACString aToAddress,
                   in ACString aEdgeName);
     void describeRoot(in ACString aAddress,
                       in unsigned long aKnownEdges);
     void describeGarbage(in ACString aAddress);
 };
 /**
  * Given an instance of this interface, the cycle collector calls the instance's
  * methods to report the objects it visits, the edges between them, and its
  * conclusions about which objects are roots and which are garbage.
  *
  * For a single cycle collection pass, the cycle collector calls this
  * interface's methods in the following order:
  *
  * - First, |begin|. If |begin| returns an error, none of the listener's other
  *   methods will be called.
  *
  * - Then, for each node in the graph:
  *   - a call to either |noteRefCountedObject| or |noteGCedObject|, to describe
  *     the node itself; and
  *   - for each edge starting at that node, a call to |noteEdge|.
  *
  * - Then, zero or more calls to |noteIncrementalRoot|; an "incremental
  *   root" is an object that may have had a new reference to it created
  *   during an incremental collection, and must therefore be treated as
  *   live for safety.
  *
  * - After all the nodes have been described, a call to |beginResults|.
  *
  * - A series of calls to:
  *   - |describeRoot|, for reference-counted nodes that the CC has identified as
  *     roots of collection. (The cycle collector didn't find enough incoming
  *     edges to account for these nodes' reference counts, so there must be code
  *     holding on to them that the cycle collector doesn't know about.)
  *   - |describeGarbage|, for nodes the cycle collector has identified as garbage.
  *
  *   Any node not mentioned in a call to |describeRoot| or |describeGarbage| is
  *   neither a root nor garbage. (The cycle collector was able to find all the
  *   edges implied by the node's reference count.)
  *
  * - Finally, a call to |end|.
  *
  *
  * This interface cannot be implemented by JavaScript code, as it is called
  * while the cycle collector works. To analyze cycle collection data in JS:
  *
  * - Create an instance of @mozilla.org/cycle-collector-logger;1, which
  *   implements this interface.
  *
  * - Set its |disableLog| property to true. This prevents the logger from
  *   printing messages about each method call to a temporary log file.
  *
  * - Set its |wantAfterProcessing| property to true. This tells the logger
  *   to record calls to its methods in memory. The |processNext| method
  *   returns events from this record.
  *
  * - Perform a collection using the logger. For example, call
  *   |nsIDOMWindowUtils|'s |garbageCollect| method, passing the logger as
  *   the |aListener| argument.
  *
  * - When the collection is complete, loop calling the logger's
  *   |processNext| method, passing a JavaScript object that implements
  *   nsICycleCollectorHandler. This JS code is free to allocate and operate
  *   on objects however it pleases: the cycle collector has finished its
  *   work, and the JS code is simply consuming recorded data.
  */
 [scriptable, builtinclass, uuid(c46e6947-9076-4a0e-bb27-d4aa3706c54d)]
 interface nsICycleCollectorListener : nsISupports
 {
     // Return a listener that directs the cycle collector to traverse
     // objects that it knows won't be collectable.
     //
     // Note that even this listener will not visit every node in the heap;
     // the cycle collector can't see the entire heap. But while this
     // listener is in use, the collector disables some optimizations it
     // normally uses to avoid certain classes of objects that are certainly
     // alive. So, if your purpose is to get a view of the portion of the
     // heap that is of interest to the cycle collector, and not simply find
     // garbage, then you should use the listener this returns.
     //
     // Note that this does not necessarily return a new listener; rather, it may
     // simply set a flag on this listener (a side effect!) and return it.
     nsICycleCollectorListener allTraces();
     // True if this listener will behave like one returned by allTraces().
     readonly attribute boolean wantAllTraces;
     // If true, do not log each method call to a temporary file.
     // Initially false.
     attribute boolean disableLog;
     // This string will appear somewhere in the log's filename.
     attribute AString filenameIdentifier;
     // If true, record all method calls in memory, to be retrieved later
     // using |processNext|. Initially false.
     attribute boolean wantAfterProcessing;
     // This string will indicate the full path of the GC log if enabled.
     readonly attribute AString gcLogPath;
     // This string will indicate the full path of the CC log if enabled.
     readonly attribute AString ccLogPath;
     void begin();
     void noteRefCountedObject (in unsigned long long aAddress,
 			       in unsigned long aRefCount,
 			       in string aObjectDescription);
     void noteGCedObject (in unsigned long long aAddress,
 			 in boolean aMarked,
 			 in string aObjectDescription,
 			 in unsigned long long aCompartmentAddress);
     void noteEdge(in unsigned long long aToAddress,
                   in string aEdgeName);
     void noteWeakMapEntry(in unsigned long long aMap,
                           in unsigned long long aKey,
                           in unsigned long long aKeyDelegate,
                           in unsigned long long aValue);
     void noteIncrementalRoot(in unsigned long long aAddress);
     void beginResults();
     void describeRoot(in unsigned long long aAddress,
 		      in unsigned long aKnownEdges);
     void describeGarbage(in unsigned long long aAddress);
     void end();
     // Report the next recorded event to |aHandler|, and remove it from the
     // record. Return false if there isn't anything more to process.
     //
     // Note that we only record events to report here if our
     // |wantAfterProcessing| property is true.
     boolean processNext(in nsICycleCollectorHandler aHandler);
 };

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xpcom/base/nsICycleCollectorListener.idl@b8a032363ba2 (annotated)

xpcom/base/nsICycleCollectorListener.idl