Bug 1194555 - Part 2: Remove |explicit| attribute from nsIMemoryReporterManager. r=njn

The calculation of |explicit| relies on the synchronous |getReportsForThisProcess|, once we have asynchronous reporters this will no longer work. As it is currently referenced in the about::memory tests we can just remove it.

toolkit/components/aboutmemory/tests/test_aboutmemory.xul

@@ -119,21 +119,6 @@
     mgr.registerStrongReporterEvenIfBlocked(fakeReporters[i]);
   }
 
-  // mgr.explicit sums "heap-allocated" and all the appropriate NONHEAP ones:
-  // - "explicit/c", "explicit/cc" x 2, "explicit/d", "explicit/e"
-  // - but *not* "explicit/c/d" x 2
-  // Check explicit now before we add the fake reporters for the fake 2nd
-  // and subsequent processes.
-  //
-  // Nb: mgr.explicit will throw NS_ERROR_NOT_AVAILABLE if this is a
-  // --disable-jemalloc build. Allow for that exception, but *only* that
-  // exception.
-  try {
-    is(mgr.explicit, 500*MB + (100 + 13 + 10)*MB + 599*KB, "mgr.explicit");
-  } catch (ex) {
-    is(ex.result, Cr.NS_ERROR_NOT_AVAILABLE, "mgr.explicit exception");
-  }
-
   // The main process always comes first when we display about:memory.  The
   // remaining processes are sorted by their |resident| values (starting with
   // the largest).  Processes without a |resident| memory reporter are saved

toolkit/components/aboutmemory/tests/test_memoryReporters.xul

@@ -141,21 +141,6 @@
   let mgr = Cc["@mozilla.org/memory-reporter-manager;1"].
             getService(Ci.nsIMemoryReporterManager);
 
-  // Access the distinguished amounts (mgr.explicit et al.) just to make sure
-  // they don't crash.  We can't check their actual values because they're
-  // non-deterministic.
-  //
-  // Nb: mgr.explicit will throw NS_ERROR_NOT_AVAILABLE if this is a
-  // --disable-jemalloc build.  Allow for that exception, but *only* that
-  // exception.
-  let dummy;
-  let haveExplicit = true;
-  try {
-    dummy = mgr.explicit;
-  } catch (ex) {
-    is(ex.result, Cr.NS_ERROR_NOT_AVAILABLE, "mgr.explicit exception");
-    haveExplicit = false;
-  }
   let amounts = [
     "vsize",
     "vsizeMaxContiguous",
@@ -182,7 +167,7 @@
       // aren't available on all platforms.  But if the attribute simply
       // isn't present, that indicates the distinguished amounts have changed
       // and this file hasn't been updated appropriately.
-      dummy = mgr[amounts[i]];
+      let dummy = mgr[amounts[i]];
       ok(dummy !== undefined,
          "accessed an unknown distinguished amount: " + amounts[i]);
     } catch (ex) {
@@ -226,9 +211,14 @@
     }
   }
 
-  // If mgr.explicit failed, we won't have "heap-allocated" either.
+  try {
-  if (haveExplicit) {
+    // Nb: mgr.heapAllocated will throw NS_ERROR_NOT_AVAILABLE if this is a
+    // --disable-jemalloc build.  Allow for skipping this test on that
+    // exception, but *only* that exception.
+    let dummy = mgr.heapAllocated;
     checkSpecialReport("heap-allocated", heapAllocatedAmounts);
+  } catch (ex) {
+    is(ex.result, Cr.NS_ERROR_NOT_AVAILABLE, "mgr.heapAllocated exception");
   }
   // vsize may be unreasonable if ASAN is enabled
   checkSpecialReport("vsize",          vsizeAmounts, /*canBeUnreasonable*/true);

xpcom/base/nsIMemoryReporter.idl

@@ -205,7 +205,7 @@ interface nsIFinishReportingCallback : nsISupports
   void callback(in nsISupports data);
 };
 
-[scriptable, builtinclass, uuid(5e4eaa5a-4808-4b97-8005-e7cdc4d73693)]
+[scriptable, builtinclass, uuid(fcad440e-64dd-4fb8-9a5e-b19d1b91423b)]
 interface nsIMemoryReporterManager : nsISupports
 {
   /*
@@ -325,11 +325,6 @@ interface nsIMemoryReporterManager : nsISupports
    * If you add a new distinguished amount, please update
    * toolkit/components/aboutmemory/tests/test_memoryReporters.xul.
    *
-   * |explicit| (UNITS_BYTES)  The total size of explicit memory allocations,
-   * both at the OS-level (eg. via mmap, VirtualAlloc) and at the heap level
-   * (eg. via malloc, calloc, operator new).  It covers all heap allocations,
-   * but will miss any OS-level ones not covered by memory reporters.
-   *
    * |vsize| (UNITS_BYTES)  The virtual size, i.e. the amount of address space
    * taken up.
    *
@@ -378,7 +373,6 @@ interface nsIMemoryReporterManager : nsISupports
    * |pageFaultsHard| (UNITS_COUNT_CUMULATIVE)  The number of hard (a.k.a.
    * major) page faults that have occurred since the process started.
    */
-  readonly attribute int64_t explicit;
   readonly attribute int64_t vsize;
   readonly attribute int64_t vsizeMaxContiguous;
   readonly attribute int64_t resident;

xpcom/base/nsMemoryReporterManager.cpp

@@ -1944,84 +1944,6 @@ nsMemoryReporterManager::UnblockRegistrationAndRestoreOriginalReporters()
   return NS_OK;
 }
 
-// This is just a wrapper for int64_t that implements nsISupports, so it can be
-// passed to nsIMemoryReporter::CollectReports.
-class Int64Wrapper final : public nsISupports
-{
-  ~Int64Wrapper() {}
-
-public:
-  NS_DECL_ISUPPORTS
-  Int64Wrapper() : mValue(0)
-  {
-  }
-  int64_t mValue;
-};
-
-NS_IMPL_ISUPPORTS0(Int64Wrapper)
-
-class ExplicitCallback final : public nsIHandleReportCallback
-{
-  ~ExplicitCallback() {}
-
-public:
-  NS_DECL_ISUPPORTS
-
-  NS_IMETHOD Callback(const nsACString& aProcess, const nsACString& aPath,
-                      int32_t aKind, int32_t aUnits, int64_t aAmount,
-                      const nsACString& aDescription,
-                      nsISupports* aWrappedExplicit) override
-  {
-    // Using the "heap-allocated" reporter here instead of
-    // nsMemoryReporterManager.heapAllocated goes against the usual
-    // pattern.  But it's for a good reason:  in tests, we can easily
-    // create artificial (i.e. deterministic) reporters -- which allows us
-    // to precisely test nsMemoryReporterManager.explicit -- but we can't
-    // do that for distinguished amounts.
-    if (aPath.EqualsLiteral("heap-allocated") ||
-        (aKind == nsIMemoryReporter::KIND_NONHEAP &&
-         PromiseFlatCString(aPath).Find("explicit") == 0)) {
-      Int64Wrapper* wrappedInt64 = static_cast<Int64Wrapper*>(aWrappedExplicit);
-      wrappedInt64->mValue += aAmount;
-    }
-    return NS_OK;
-  }
-};
-
-NS_IMPL_ISUPPORTS(ExplicitCallback, nsIHandleReportCallback)
-
-NS_IMETHODIMP
-nsMemoryReporterManager::GetExplicit(int64_t* aAmount)
-{
-  if (NS_WARN_IF(!aAmount)) {
-    return NS_ERROR_INVALID_ARG;
-  }
-  *aAmount = 0;
-#ifndef HAVE_JEMALLOC_STATS
-  return NS_ERROR_NOT_AVAILABLE;
-#else
-
-  // For each reporter we call CollectReports and filter out the
-  // non-explicit, non-NONHEAP measurements (except for "heap-allocated").
-  // That's lots of wasted work, and we used to have a GetExplicitNonHeap()
-  // method which did this more efficiently, but it ended up being more
-  // trouble than it was worth.
-
-  nsRefPtr<ExplicitCallback> handleReport = new ExplicitCallback();
-  nsRefPtr<Int64Wrapper> wrappedExplicitSize = new Int64Wrapper();
-
-  // Anonymization doesn't matter here, because we're only summing all the
-  // reported values. Enable it anyway because it's slightly faster, since it
-  // doesn't have to get URLs, find notable strings, etc.
-  GetReportsForThisProcess(handleReport, wrappedExplicitSize,
-                           /* anonymize = */ true);
-
-  *aAmount = wrappedExplicitSize->mValue;
-
-  return NS_OK;
-#endif // HAVE_JEMALLOC_STATS
-}
-
 NS_IMETHODIMP
 nsMemoryReporterManager::GetVsize(int64_t* aVsize)
 {