Bug 1675203 - Backed out changeset 0bcd9a5ae49f (Bug 1667581) for causing memory usage regressions a=backout

Differential Revision: https://phabricator.services.mozilla.com/D96007

xpcom/io/nsSegmentedBuffer.cpp

@@ -113,6 +113,43 @@ void nsSegmentedBuffer::Empty() {
   mFirstSegmentIndex = mLastSegmentIndex = 0;
 }
 
+#if 0
+void
+TestSegmentedBuffer()
+{
+  nsSegmentedBuffer* buf = new nsSegmentedBuffer();
+  NS_ASSERTION(buf, "out of memory");
+  buf->Init(4, 16);
+  char* seg;
+  bool empty;
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  seg = buf->AppendNewSegment();
+  NS_ASSERTION(seg, "AppendNewSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(!empty, "DeleteFirstSegment failed");
+  empty = buf->DeleteFirstSegment();
+  NS_ASSERTION(empty, "DeleteFirstSegment failed");
+  delete buf;
+}
+#endif
+
 void nsSegmentedBuffer::FreeOMT(void* aPtr) {
   if (!NS_IsMainThread()) {
     free(aPtr);
@@ -122,16 +159,13 @@ void nsSegmentedBuffer::FreeOMT(void* aPtr) {
   nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction("nsSegmentedBuffer::FreeOMT",
                                                    [aPtr]() { free(aPtr); });
 
-  nsresult rv = NS_OK;
-  if (!mFreeMemoryQueue) {
-    rv = NS_CreateBackgroundTaskQueue("nsSegmentedBuffer::FreeOMT",
-                                      getter_AddRefs(mFreeMemoryQueue));
+  if (!mIOThread) {
+    mIOThread = do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID);
   }
 
-  // During the shutdown we are not able to obtain the thread and/or the
+  // During the shutdown we are not able to obtain the IOThread and/or the
   // dispatching of runnable fails.
-  if (NS_FAILED(rv) || !mFreeMemoryQueue ||
-      NS_FAILED(mFreeMemoryQueue->Dispatch(r.forget()))) {
+  if (!mIOThread || NS_FAILED(mIOThread->Dispatch(r.forget()))) {
     free(aPtr);
   }
 }

xpcom/io/nsSegmentedBuffer.h

@@ -84,8 +84,7 @@ class nsSegmentedBuffer {
  private:
   void FreeOMT(void* aPtr);
 
-  // This event queue is used to free segment memory.
-  nsCOMPtr<nsISerialEventTarget> mFreeMemoryQueue;
+  nsCOMPtr<nsIEventTarget> mIOThread;
 };
 
 // NS_SEGMENTARRAY_INITIAL_SIZE: This number needs to start out as a

xpcom/tests/gtest/TestSegmentedBuffer.cpp

@@ -1,40 +0,0 @@
-/* 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 "gtest/gtest.h"
-#include "../../io/nsSegmentedBuffer.h"
-
-using namespace mozilla;
-
-TEST(SegmentedBuffer, AppendAndDelete)
-{
-  auto buf = MakeUnique<nsSegmentedBuffer>();
-  buf->Init(4, 16);
-  char* seg;
-  bool empty;
-  seg = buf->AppendNewSegment();
-  EXPECT_TRUE(seg) << "AppendNewSegment failed";
-  seg = buf->AppendNewSegment();
-  EXPECT_TRUE(seg) << "AppendNewSegment failed";
-  seg = buf->AppendNewSegment();
-  EXPECT_TRUE(seg) << "AppendNewSegment failed";
-  empty = buf->DeleteFirstSegment();
-  EXPECT_TRUE(!empty) << "DeleteFirstSegment failed";
-  empty = buf->DeleteFirstSegment();
-  EXPECT_TRUE(!empty) << "DeleteFirstSegment failed";
-  seg = buf->AppendNewSegment();
-  EXPECT_TRUE(seg) << "AppendNewSegment failed";
-  seg = buf->AppendNewSegment();
-  EXPECT_TRUE(seg) << "AppendNewSegment failed";
-  seg = buf->AppendNewSegment();
-  EXPECT_TRUE(seg) << "AppendNewSegment failed";
-  empty = buf->DeleteFirstSegment();
-  EXPECT_TRUE(!empty) << "DeleteFirstSegment failed";
-  empty = buf->DeleteFirstSegment();
-  EXPECT_TRUE(!empty) << "DeleteFirstSegment failed";
-  empty = buf->DeleteFirstSegment();
-  EXPECT_TRUE(!empty) << "DeleteFirstSegment failed";
-  empty = buf->DeleteFirstSegment();
-  EXPECT_TRUE(empty) << "DeleteFirstSegment failed";
-}

xpcom/tests/gtest/moz.build

@@ -40,7 +40,6 @@ UNIFIED_SOURCES += [
     "TestRacingServiceManager.cpp",
     "TestRecursiveMutex.cpp",
     "TestRWLock.cpp",
-    "TestSegmentedBuffer.cpp",
     "TestSlicedInputStream.cpp",
     "TestSmallArrayLRUCache.cpp",
     "TestSnappyStreams.cpp",