bug 585196: Cycle-collector telemetry probe r=bent

xpcom/base/nsCycleCollector.cpp

@@ -125,6 +125,7 @@
 #endif
 #endif
 
+#include "base/basictypes.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsCycleCollectorUtils.h"
 #include "nsIProgrammingLanguage.h"
@@ -151,7 +152,8 @@
 #include "nsIXPConnect.h"
 #include "nsIJSRuntimeService.h"
 #include "xpcpublic.h"
-
+#include "base/histogram.h"
+#include "base/logging.h"
 #include <stdio.h>
 #include <string.h>
 #ifdef WIN32
@@ -981,7 +983,7 @@ struct nsCycleCollector
     PRBool mFollowupCollection;
     PRUint32 mCollectedObjects;
     PRBool mFirstCollection;
-    PRTime mCollectionStart;
+    TimeStamp mCollectionStart;
 
     nsCycleCollectionLanguageRuntime *mRuntimes[nsIProgrammingLanguage::MAX+1];
     nsCycleCollectionXPCOMRuntime mXPCOMRuntime;
@@ -2477,8 +2479,8 @@ nsCycleCollector::PrepareForCollection(nsTPtrArray<PtrInfo> *aWhiteNodes)
 
 #ifdef COLLECT_TIME_DEBUG
     printf("cc: nsCycleCollector::PrepareForCollection()\n");
-    mCollectionStart = PR_Now();
 #endif
+    mCollectionStart = TimeStamp::Now();
 
     mCollectionInProgress = PR_TRUE;
 
@@ -2508,10 +2510,13 @@ nsCycleCollector::CleanupAfterCollection()
     _heapmin();
 #endif
 
+    PRUint32 interval((TimeStamp::Now() - mCollectionStart).ToMilliseconds());
 #ifdef COLLECT_TIME_DEBUG
-    printf("cc: CleanupAfterCollection(), total time %lldms\n",
-           (PR_Now() - mCollectionStart) / PR_USEC_PER_MSEC);
+    printf("cc: CleanupAfterCollection(), total time %ums\n", interval);
 #endif
+    UMA_HISTOGRAM_TIMES("nsCycleCollector::Collect (ms)",
+                        base::TimeDelta::FromMilliseconds(interval));
+
 #ifdef DEBUG_CC
     ExplainLiveExpectedGarbage();
 #endif