Patch v0, Avoid a massive number of XPConnect calls when using memory reporters

mem-xpc-reduce-v0.diff

# HG changeset patch
# Parent 1987beeb0038e84eddd39d3026388ba361dc0cf2
Avoid a massive number of XPConnect calls when using memory reporters

diff --git a/toolkit/components/aboutmemory/content/aboutMemory.js b/toolkit/components/aboutmemory/content/aboutMemory.js
--- a/toolkit/components/aboutmemory/content/aboutMemory.js
+++ b/toolkit/components/aboutmemory/content/aboutMemory.js
@@ -149,17 +149,13 @@ function minimizeMemoryUsage3x(fAfter)
  *
  * @param aMgr
  *        The memory reporter manager.
- * @param aIgnoreSingle
- *        Function that indicates if we should skip a single reporter, based
- *        on its path.
- * @param aIgnoreMulti
- *        Function that indicates if we should skip a multi-reporter, based on
- *        its name.
+ * @param aIgnore
+ *        Function that indicates if we should skip a reporter, based on its
+ *        path.
  * @param aHandleReport
  *        The function that's called for each report.
  */
-function processMemoryReporters(aMgr, aIgnoreSingle, aIgnoreMulti,
-                                aHandleReport)
+function processMemoryReporters(aMgr, aIgnore, aHandleReport)
 {
   // Process each memory reporter with aHandleReport.
   //
@@ -171,54 +167,19 @@ function processMemoryReporters(aMgr, aI
   //
   // - After this point we never use the original memory report again.
 
-  function handleReport(aProcess, aUnsafePath, aKind, aUnits, aAmount,
-                        aDescription)
-  {
-    checkReport(aUnsafePath, aKind, aUnits, aAmount, aDescription);
-    aHandleReport(aProcess, aUnsafePath, aKind, aUnits, aAmount, aDescription);
-  }
-
-  let e = aMgr.enumerateReporters();
-  while (e.hasMoreElements()) {
-    let rOrig = e.getNext().QueryInterface(Ci.nsIMemoryReporter);
-    let unsafePath;
+  let reports = aMgr.collectAllReports();
+  for (let i = reports.length; ~--i;) {
+    let {
+      process, path, kind, units, amount, description
+    } = reports[i];
     try {
-      unsafePath = rOrig.path;
-      if (!aIgnoreSingle(unsafePath)) {
-        handleReport(rOrig.process, unsafePath, rOrig.kind, rOrig.units, 
-                     rOrig.amount, rOrig.description);
+      if (!aIgnore(path)) {
+        checkReport(path, kind, units, amount, description);
+        aHandleReport(process, path, kind, units, amount, description);
       }
     }
     catch (ex) {
-      debug("Exception thrown by memory reporter: " + unsafePath + ": " + ex);
-    }
-  }
-
-  let e = aMgr.enumerateMultiReporters();
-  while (e.hasMoreElements()) {
-    let mr = e.getNext().QueryInterface(Ci.nsIMemoryMultiReporter);
-    let name = mr.name;
-    try {
-      if (!aIgnoreMulti(name)) {
-        mr.collectReports(handleReport, null);
-      }
-    }
-    catch (ex) {
-      // There are two exception cases that must be distinguished here.
-      //
-      // - We want to halt proceedings on exceptions thrown within this file
-      //   (i.e. assertion failures in handleReport);  such exceptions contain
-      //   gAssertionFailureMsgPrefix in their string representation.
-      //
-      // - We want to continue on when faced with exceptions thrown outside
-      //   this file (i.e. when measuring an amount in collectReports).
-      let str = ex.toString();
-      if (str.search(gAssertionFailureMsgPrefix) >= 0) {
-        throw(ex); 
-      } else {
-        debug("Exception thrown within memory multi-reporter: " + name + ": " +
-              ex);
-      }
+      debug("Exception thrown by memory reporter: " + path + ": " + ex);
     }
   }
 }
@@ -503,20 +464,14 @@ function getReportsByProcess(aMgr)
   // that reports from these multi-reporters can reach here as single reports
   // if they were in the child process.)
 
-  function ignoreSingle(aUnsafePath) 
+  function ignore(aUnsafePath) 
   {
     return (isSmapsPath(aUnsafePath) && !gVerbose) ||
+           aUnsafePath.startsWith("smaps/") ||
            aUnsafePath.startsWith("compartments/") ||
            aUnsafePath.startsWith("ghost-windows/");
   }
 
-  function ignoreMulti(aMRName)
-  {
-    return (aMRName === "smaps" && !gVerbose) ||
-           aMRName === "compartments" ||
-           aMRName === "ghost-windows";
-  }
-
   let reportsByProcess = {};
 
   function handleReport(aProcess, aUnsafePath, aKind, aUnits, aAmount,
@@ -538,7 +493,7 @@ function getReportsByProcess(aMgr)
     }
   }
 
-  processMemoryReporters(aMgr, ignoreSingle, ignoreMulti, handleReport);
+  processMemoryReporters(aMgr, ignore, handleReport);
 
   return reportsByProcess;
 }
@@ -1531,16 +1486,11 @@ function getCompartmentsByProcess(aMgr)
   // (Note that some such reports can reach here as single reports if they were
   // in the child process.)
 
-  function ignoreSingle(aUnsafePath) 
+  function ignore(aUnsafePath) 
   {
     return !aUnsafePath.startsWith("compartments/");
   }
 
-  function ignoreMulti(aMRName)
-  {
-    return aMRName !== "compartments";
-  }
-
   let compartmentsByProcess = {};
 
   function handleReport(aProcess, aUnsafePath, aKind, aUnits, aAmount,
@@ -1584,7 +1534,7 @@ function getCompartmentsByProcess(aMgr)
     }
   }
 
-  processMemoryReporters(aMgr, ignoreSingle, ignoreMulti, handleReport);
+  processMemoryReporters(aMgr, ignore, handleReport);
 
   return compartmentsByProcess;
 }
@@ -1606,16 +1556,11 @@ GhostWindow.prototype = {
 
 function getGhostWindowsByProcess(aMgr)
 {
-  function ignoreSingle(aUnsafePath) 
+  function ignore(aUnsafePath) 
   {
     return !aUnsafePath.startsWith('ghost-windows/')
   }
 
-  function ignoreMulti(aName)
-  {
-    return aName !== "ghost-windows";
-  }
-
   let ghostWindowsByProcess = {};
 
   function handleReport(aProcess, aUnsafePath, aKind, aUnits, aAmount,
@@ -1641,7 +1586,7 @@ function getGhostWindowsByProcess(aMgr)
     }
   }
 
-  processMemoryReporters(aMgr, ignoreSingle, ignoreMulti, handleReport);
+  processMemoryReporters(aMgr, ignore, handleReport);
 
   return ghostWindowsByProcess;
 }
diff --git a/xpcom/base/nsIMemoryReporter.idl b/xpcom/base/nsIMemoryReporter.idl
--- a/xpcom/base/nsIMemoryReporter.idl
+++ b/xpcom/base/nsIMemoryReporter.idl
@@ -237,7 +237,7 @@ interface nsIMemoryMultiReporter : nsISu
   readonly attribute PRInt64 explicitNonHeap;
 };
 
-[scriptable, uuid(4527b1d8-a81f-4af3-9623-80e4120392c7)]
+[scriptable, uuid(203e5380-a6c1-11e1-b3dd-0800200c9a66)]
 interface nsIMemoryReporterManager : nsISupports
 {
   /*
@@ -303,6 +303,14 @@ interface nsIMemoryReporterManager : nsI
    * This attribute indicates if moz_malloc_usable_size() works.
    */
   readonly attribute boolean hasMozMallocUsableSize;
+
+  /*
+   * Collect all reports in a Javascript array. This will avoid a lot of
+   * XPConnect calls and also simplifies the JS consumers, such as
+   * about:memory.
+   * This function should only be called from Javascript.
+   */
+  [implicit_jscontext] jsval collectAllReports();
 };
 
 %{C++
diff --git a/xpcom/base/nsMemoryReporterManager.cpp b/xpcom/base/nsMemoryReporterManager.cpp
--- a/xpcom/base/nsMemoryReporterManager.cpp
+++ b/xpcom/base/nsMemoryReporterManager.cpp
@@ -12,6 +12,8 @@
 #include "nsISimpleEnumerator.h"
 #include "mozilla/Telemetry.h"
 
+#include "jsapi.h"
+
 using namespace mozilla;
 
 #if defined(MOZ_MEMORY)
@@ -838,6 +840,178 @@ nsMemoryReporterManager::GetHasMozMalloc
     return NS_OK;
 }
 
+class CollectAllReportersCallback: public nsIMemoryMultiReporterCallback
+{
+private:
+    static void finalize(const JSStringFinalizer *fin, jschar *chars) {
+        nsMemory::Free(chars);
+    }
+    static const JSStringFinalizer finalizer;
+
+    JSContext *cx;
+    JSObject *array;
+
+    inline
+    bool setString(JSObject *obj, const char *name, const nsACString &str)
+    {
+        if (str.IsVoid()) {
+            return JS_DefineProperty(cx, obj, name, JSVAL_NULL, NULL, NULL, JSPROP_ENUMERATE);
+        }
+        JSString *jsstr = JS_NewStringCopyN(cx, str.BeginReading(), str.Length());
+        if (!jsstr) {
+            return false;
+        }
+        return JS_DefineProperty(cx, obj, name, STRING_TO_JSVAL(jsstr), NULL, NULL, JSPROP_ENUMERATE);
+    }
+    inline
+    bool setUtf8String(JSObject *obj, const char *name, const nsACString &str)
+    {
+        if (str.IsVoid()) {
+            return JS_DefineProperty(cx, obj, name, JSVAL_NULL, NULL, NULL, JSPROP_ENUMERATE);
+        }
+        PRUint32 len;
+        jschar *chars = (jschar *)UTF8ToNewUnicode(str, &len);
+        if (!chars) {
+            return false;
+        }
+        JSString *jsstr = JS_NewExternalString(cx, chars, len, &finalizer);
+        if (!jsstr) {
+            finalize(NULL, chars);
+            return false;
+        }
+        return JS_DefineProperty(cx, obj, name, STRING_TO_JSVAL(jsstr), NULL, NULL, JSPROP_ENUMERATE);
+    }
+    inline
+    bool setPRInt32(JSObject *obj, const char *name, const PRInt32 value)
+    {
+        return JS_DefineProperty(cx, obj, name, INT_TO_JSVAL((int32_t)value), NULL, NULL, JSPROP_ENUMERATE);
+    }
+    inline
+    bool setPRInt64(JSObject *obj, const char *name, const PRInt64 value)
+    {
+        return JS_DefineProperty(cx, obj, name, DOUBLE_TO_JSVAL(double(value)), NULL, NULL, JSPROP_ENUMERATE);
+    }
+
+public:
+    CollectAllReportersCallback(JSContext *aCx, JSObject *aArray)
+        : cx(aCx), array(aArray)
+    {}
+
+    NS_DECL_ISUPPORTS
+
+    NS_IMETHOD Callback(const nsACString &aProcess, const nsACString &aPath,
+                        PRInt32 aKind, PRInt32 aUnits, PRInt64 aAmount,
+                        const nsACString &aDescription, nsISupports *aData);
+};
+const JSStringFinalizer CollectAllReportersCallback::finalizer =
+    { CollectAllReportersCallback::finalize };
+
+NS_IMPL_ISUPPORTS1(CollectAllReportersCallback, nsIMemoryMultiReporterCallback)
+
+NS_IMETHODIMP CollectAllReportersCallback::Callback(const nsACString &aProcess,
+                                                    const nsACString &aPath,
+                                                    PRInt32 aKind,
+                                                    PRInt32 aUnits,
+                                                    PRInt64 aAmount,
+                                                    const nsACString &aDescription,
+                                                    nsISupports *aData)
+{
+    JSObject *obj = JS_NewObject(cx, NULL, NULL, NULL);
+    if (!obj) {
+        return NS_ERROR_FAILURE;
+    }
+    JS::AutoObjectRooter rd(cx, obj);
+
+    if (!setString(obj, "process", aProcess)
+        || !setUtf8String(obj, "path", aPath)
+        || !setPRInt32(obj, "kind", aKind)
+        || !setPRInt32(obj, "units", aUnits)
+        || !setPRInt64(obj, "amount", aAmount)
+        || !setUtf8String(obj, "description", aDescription)) {
+        return NS_ERROR_FAILURE;
+    }
+
+    jsval objval = OBJECT_TO_JSVAL(obj);
+    uint32_t length;
+    if (!JS_GetArrayLength(cx, array, &length)) {
+        return NS_ERROR_FAILURE;
+    }
+    if (!JS_SetElement(cx, array, length, &objval)) {
+        return NS_ERROR_FAILURE;
+    }
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsMemoryReporterManager::CollectAllReports(JSContext *cx, jsval *aRetVal)
+{
+    nsresult rv;
+    JSObject *array = JS_NewArrayObject(cx, 0, NULL);
+    if (!array) {
+        return NS_ERROR_FAILURE;
+    }
+    JS::AutoObjectRooter rd(cx, array);
+
+    nsRefPtr<CollectAllReportersCallback> collector =
+        new CollectAllReportersCallback(cx, array);
+
+    // Process regular reporters
+    bool more;
+    nsCOMPtr<nsISimpleEnumerator> eSingle;
+    if (NS_FAILED(rv = EnumerateReporters(getter_AddRefs(eSingle)))) {
+        return rv;
+    }
+    nsCString process, path, description;
+    PRInt32 kind, units;
+    PRInt64 amount;
+    nsCOMPtr<nsIMemoryReporter> reporter;
+    while (NS_SUCCEEDED(eSingle->HasMoreElements(&more)) && more) {
+        if (NS_FAILED(rv = eSingle->GetNext(getter_AddRefs(reporter)))) {
+            return rv;
+        }
+        if (NS_FAILED(rv = reporter->GetProcess(process))) {
+            return rv;
+        }
+        if (NS_FAILED(rv = reporter->GetPath(path))) {
+            return rv;
+        }
+        if (NS_FAILED(rv = reporter->GetDescription(description))) {
+            return rv;
+        }
+        if (NS_FAILED(rv = reporter->GetKind(&kind))) {
+            return rv;
+        }
+        if (NS_FAILED(rv = reporter->GetUnits(&units))) {
+            return rv;
+        }
+        if (NS_FAILED(rv = reporter->GetAmount(&amount))) {
+            return rv;
+        }
+        if (NS_FAILED(rv = collector->Callback(process, path, kind, units,
+                                               amount, description, nsnull))) {
+            return rv;
+        }
+    }
+
+    // Process multi reporters
+    nsCOMPtr<nsISimpleEnumerator> eMulti;
+    if (NS_FAILED(rv = EnumerateMultiReporters(getter_AddRefs(eMulti)))) {
+        return rv;
+    }
+    nsCOMPtr<nsIMemoryMultiReporter> multiReporter;
+    while (NS_SUCCEEDED(eMulti->HasMoreElements(&more)) && more) {
+        if (NS_FAILED(rv = eMulti->GetNext(getter_AddRefs(multiReporter)))) {
+            return rv;
+        }
+        if (NS_FAILED(rv = multiReporter->CollectReports(collector, nsnull))) {
+            return rv;
+        }
+    }
+
+    *aRetVal = OBJECT_TO_JSVAL(array);
+    return NS_OK;
+}
+
 NS_IMPL_ISUPPORTS1(nsMemoryReporter, nsIMemoryReporter)
 
 nsMemoryReporter::nsMemoryReporter(nsACString& process,