Backed out changeset 8e247550d6cf (bug 1411984) for bustage.

layout/printing/DrawEventRecorder.h

@@ -15,28 +15,18 @@ namespace mozilla {
 namespace layout {
 
 class PRFileDescStream : public mozilla::gfx::EventStream {
-  // Most writes, as seen in the print IPC use case, are very small (<32 bytes),
-  // with a small number of very large (>40KB) writes. Writes larger than this
-  // value are not buffered.
-  static const size_t kBufferSize = 1024;
 public:
-  PRFileDescStream() : mFd(nullptr), mBuffer(nullptr), mBufferPos(0),
-                       mGood(true) {}
+  PRFileDescStream() : mFd(nullptr), mGood(true) {}
 
   void OpenFD(PRFileDesc* aFd) {
     MOZ_ASSERT(!IsOpen());
     mFd = aFd;
     mGood = true;
-    mBuffer.reset(new uint8_t[kBufferSize]);
-    mBufferPos = 0;
   }
 
   void Close() {
-    Flush();
     PR_Close(mFd);
     mFd = nullptr;
-    mBuffer.reset();
-    mBufferPos = 0;
   }
 
   bool IsOpen() {
@@ -44,46 +34,23 @@ public:
   }
 
   void Flush() {
-    // We need to be API compatible with std::ostream, and so we silently handle
-    // flushes on a closed FD.
-    if (IsOpen() && mBufferPos > 0) {
-      PR_Write(mFd, static_cast<const void*>(mBuffer.get()), mBufferPos);
-      mBufferPos = 0;
-    }
+    // For std::ostream this flushes any internal buffers. PRFileDesc's IO isn't
+    // buffered, so nothing to do here.
   }
 
   void Seek(PRInt32 aOffset, PRSeekWhence aWhence) {
-    Flush();
     PR_Seek(mFd, aOffset, aWhence);
   }
 
   void write(const char* aData, size_t aSize) {
-    // See comment in Flush().
+    // We need to be API compatible with std::ostream, and so we silently handle
+    // writes on a closed FD.
     if (IsOpen()) {
-      // If we're writing more data than could ever fit in our buffer, flush the
-      // buffer and write directly.
-      if (aSize > kBufferSize) {
-        Flush();
-        PR_Write(mFd, static_cast<const void*>(aData), aSize);
-      // If our write could fit in our buffer, but doesn't because the buffer is
-      // partially full, write to the buffer, flush the buffer, and then write
-      // the rest of the data to the buffer.
-      } else if (aSize > AvailableBufferSpace()) {
-        size_t length = AvailableBufferSpace();
-        WriteToBuffer(aData, length);
-        Flush();
-
-        MOZ_ASSERT(aSize <= kBufferSize);
-        WriteToBuffer(aData + length, aSize - length);
-      // Write fits in the buffer.
-      } else {
-        WriteToBuffer(aData, aSize);
-      }
+      PR_Write(mFd, static_cast<const void*>(aData), aSize);
     }
   }
 
   void read(char* aOut, size_t aSize) {
-    Flush();
     PRInt32 res = PR_Read(mFd, static_cast<void*>(aOut), aSize);
     mGood = res >= 0 && ((size_t)res == aSize);
   }
@@ -93,19 +60,7 @@ public:
   }
 
 private:
-  size_t AvailableBufferSpace() {
-    return kBufferSize - mBufferPos;
-  }
-
-  void WriteToBuffer(const char* aData, size_t aSize) {
-    MOZ_ASSERT(aSize <= AvailableBufferSpace());
-    memcpy(mBuffer.get() + mBufferPos, aData, aSize);
-    mBufferPos += aSize;
-  }
-
   PRFileDesc* mFd;
-  std::unique_ptr<uint8_t[]> mBuffer;
-  size_t mBufferPos;
   bool mGood;
 };