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Bug 1059859 - Fix race condition in CrashManager._getStore() resulting in multiple stores being created. r=gps

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This commit is contained in:
Birunthan Mohanathas 2014-08-29 13:38:57 -07:00
parent 38c41f731b
commit f102d8b356
1 changed files with 48 additions and 34 deletions
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82
toolkit/components/crashes/CrashManager.jsm
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@ -112,6 +112,10 @@ this.CrashManager = function (options) {
// The CrashStore currently attached to this object.
this._store = null;
// A Task to retrieve the store. This is needed to avoid races when
// _getStore() is called multiple times in a short interval.
this._getStoreTask = null;
// The timer controlling the expiration of the CrashStore instance.
this._storeTimer = null;
@ -575,47 +579,57 @@ this.CrashManager.prototype = Object.freeze({
},
_getStore: function () {
return Task.spawn(function* () {
if (!this._store) {
yield OS.File.makeDir(this._storeDir, {
ignoreExisting: true,
unixMode: OS.Constants.libc.S_IRWXU,
});
if (this._getStoreTask) {
return this._getStoreTask;
}
let store = new CrashStore(this._storeDir, this._telemetryStoreSizeKey);
yield store.load();
return this._getStoreTask = Task.spawn(function* () {
try {
if (!this._store) {
yield OS.File.makeDir(this._storeDir, {
ignoreExisting: true,
unixMode: OS.Constants.libc.S_IRWXU,
});
this._store = store;
this._storeTimer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
}
let store = new CrashStore(this._storeDir,
this._telemetryStoreSizeKey);
yield store.load();
// The application can go long periods without interacting with the
// store. Since the store takes up resources, we automatically "free"
// the store after inactivity so resources can be returned to the system.
// We do this via a timer and a mechanism that tracks when the store
// is being accessed.
this._storeTimer.cancel();
// This callback frees resources from the store unless the store
// is protected from freeing by some other process.
let timerCB = function () {
if (this._storeProtectedCount) {
this._storeTimer.initWithCallback(timerCB, this.STORE_EXPIRATION_MS,
this._storeTimer.TYPE_ONE_SHOT);
return;
this._store = store;
this._storeTimer = Cc["@mozilla.org/timer;1"]
.createInstance(Ci.nsITimer);
}
// We kill the reference that we hold. GC will kill it later. If
// someone else holds a reference, that will prevent GC until that
// reference is gone.
this._store = null;
this._storeTimer = null;
}.bind(this);
// The application can go long periods without interacting with the
// store. Since the store takes up resources, we automatically "free"
// the store after inactivity so resources can be returned to the
// system. We do this via a timer and a mechanism that tracks when the
// store is being accessed.
this._storeTimer.cancel();
this._storeTimer.initWithCallback(timerCB, this.STORE_EXPIRATION_MS,
this._storeTimer.TYPE_ONE_SHOT);
// This callback frees resources from the store unless the store
// is protected from freeing by some other process.
let timerCB = function () {
if (this._storeProtectedCount) {
this._storeTimer.initWithCallback(timerCB, this.STORE_EXPIRATION_MS,
this._storeTimer.TYPE_ONE_SHOT);
return;
}
return this._store;
// We kill the reference that we hold. GC will kill it later. If
// someone else holds a reference, that will prevent GC until that
// reference is gone.
this._store = null;
this._storeTimer = null;
}.bind(this);
this._storeTimer.initWithCallback(timerCB, this.STORE_EXPIRATION_MS,
this._storeTimer.TYPE_ONE_SHOT);
return this._store;
} finally {
this._getStoreTask = null;
}
}.bind(this));
},