Coalesce small buffers in net::BidirectionalStream

components/cronet/android/java/src/org/chromium/net/CronetBidirectionalStream.java

Index: components/cronet/android/java/src/org/chromium/net/CronetBidirectionalStream.java
diff --git a/components/cronet/android/java/src/org/chromium/net/CronetBidirectionalStream.java b/components/cronet/android/java/src/org/chromium/net/CronetBidirectionalStream.java
index 4c0fae741dbf49d5534a516ada1703a9e03fb8b0..188e1766ff57082a5a8052d4e229cf31ecd957dc 100644
--- a/components/cronet/android/java/src/org/chromium/net/CronetBidirectionalStream.java
+++ b/components/cronet/android/java/src/org/chromium/net/CronetBidirectionalStream.java
@@ -14,6 +14,7 @@ import java.nio.ByteBuffer;
 import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.Executor;
@@ -54,9 +55,9 @@ class CronetBidirectionalStream extends BidirectionalStream {
         ERROR,
         /* Reading and writing are done, and the stream is closed successfully. */
         SUCCESS,
-        /* Waiting for {@code write()} to be called. */
+        /* Waiting for {@code nativeWritevData()} to be called. */
         WAITING_FOR_WRITE,
-        /* Writing to the remote, {@code onWriteCompleted()} callback will be called when done. */
+        /* Writing to the remote, {@code onWritevCompleted()} callback will be called when done. */
         WRITING,
         /* There is no more data to write and stream is half-closed by the local side. */
         WRITING_DONE,
@@ -69,12 +70,26 @@ class CronetBidirectionalStream extends BidirectionalStream {
     private final int mInitialPriority;
     private final String mInitialMethod;
     private final String mRequestHeaders[];
+    private final boolean mDisableAutoFlush;
 
     /*
      * Synchronizes access to mNativeStream, mReadState and mWriteState.
      */
     private final Object mNativeStreamLock = new Object();
 
+    @GuardedBy("mNativeStreamLock")
+    // Pending write data.
+    private LinkedList<ByteBuffer> mPendingData;
+
+    @GuardedBy("mNativeStreamLock")
+    // Flush data queue that should be pushed to the native stack when the previous
+    // nativeWritevData completes.
+    private LinkedList<ByteBuffer> mFlushData;
+
+    @GuardedBy("mNativeStreamLock")
+    // Whether an end-of-stream flag is passed in through write().
+    private boolean mEndOfStreamWritten;
+
     /* Native BidirectionalStream object, owned by CronetBidirectionalStream. */
     @GuardedBy("mNativeStreamLock")
     private long mNativeStream;
@@ -91,28 +106,24 @@ class CronetBidirectionalStream extends BidirectionalStream {
 
     /**
      * Write state is tracking writing flow.
-     *                         / <--- WRITING <---  \
-     *                         |                    |
-     *                         \                    /
+     *                         / <---  WRITING  <--- \
+     *                         |                     |
+     *                         \                     /
      * NOT_STARTED -> STARTED --> WAITING_FOR_WRITE -> WRITING_DONE -> SUCCESS
      */
     @GuardedBy("mNativeStreamLock")
     private State mWriteState = State.NOT_STARTED;
 
+    // Only modified on the network thread.
     private UrlResponseInfo mResponseInfo;
 
     /*
      * OnReadCompleted callback is repeatedly invoked when each read is completed, so it
      * is cached as a member variable.
      */
+    // Only modified on the network thread.
     private OnReadCompletedRunnable mOnReadCompletedTask;
 
-    /*
-     * OnWriteCompleted callback is repeatedly invoked when each write is completed, so it
-     * is cached as a member variable.
-     */
-    private OnWriteCompletedRunnable mOnWriteCompletedTask;
-
     private Runnable mOnDestroyedCallbackForTesting;
 
     private final class OnReadCompletedRunnable implements Runnable {
@@ -127,20 +138,23 @@ class CronetBidirectionalStream extends BidirectionalStream {
                 // Null out mByteBuffer, to pass buffer ownership to callback or release if done.
                 ByteBuffer buffer = mByteBuffer;
                 mByteBuffer = null;
+                boolean maybeOnSucceeded = false;
                 synchronized (mNativeStreamLock) {
                     if (isDoneLocked()) {
                         return;
                     }
                     if (mEndOfStream) {
                         mReadState = State.READING_DONE;
-                        if (maybeSucceedLocked()) {
-                            return;
-                        }
+                        maybeOnSucceeded = (mWriteState == State.WRITING_DONE);
                     } else {
                         mReadState = State.WAITING_FOR_READ;
                     }
                 }
-                mCallback.onReadCompleted(CronetBidirectionalStream.this, mResponseInfo, buffer);
+                mCallback.onReadCompleted(
+                        CronetBidirectionalStream.this, mResponseInfo, buffer, mEndOfStream);
+                if (maybeOnSucceeded) {
+                    maybeOnSucceededOnExecutor();
+                }
             } catch (Exception e) {
                 onCallbackException(e);
             }
@@ -149,9 +163,14 @@ class CronetBidirectionalStream extends BidirectionalStream {
 
     private final class OnWriteCompletedRunnable implements Runnable {
         // Buffer passed back from current invocation of onWriteCompleted.
-        ByteBuffer mByteBuffer;
+        private ByteBuffer mByteBuffer;
         // End of stream flag from current call to write.
-        boolean mEndOfStream;
+        private final boolean mEndOfStream;
+
+        OnWriteCompletedRunnable(ByteBuffer buffer, boolean endOfStream) {
+            mByteBuffer = buffer;
+            mEndOfStream = endOfStream;
+        }
 
         @Override
         public void run() {
@@ -159,20 +178,21 @@ class CronetBidirectionalStream extends BidirectionalStream {
                 // Null out mByteBuffer, to pass buffer ownership to callback or release if done.
                 ByteBuffer buffer = mByteBuffer;
                 mByteBuffer = null;
+                boolean maybeOnSucceeded = false;
                 synchronized (mNativeStreamLock) {
                     if (isDoneLocked()) {
                         return;
                     }
                     if (mEndOfStream) {
                         mWriteState = State.WRITING_DONE;
-                        if (maybeSucceedLocked()) {
-                            return;
-                        }
-                    } else {
-                        mWriteState = State.WAITING_FOR_WRITE;
+                        maybeOnSucceeded = (mReadState == State.READING_DONE);
                     }
                 }
-                mCallback.onWriteCompleted(CronetBidirectionalStream.this, mResponseInfo, buffer);
+                mCallback.onWriteCompleted(
+                        CronetBidirectionalStream.this, mResponseInfo, buffer, mEndOfStream);
+                if (maybeOnSucceeded) {
+                    maybeOnSucceededOnExecutor();
+                }
             } catch (Exception e) {
                 onCallbackException(e);
             }
@@ -181,7 +201,8 @@ class CronetBidirectionalStream extends BidirectionalStream {
 
     CronetBidirectionalStream(CronetUrlRequestContext requestContext, String url,
             @BidirectionalStream.Builder.StreamPriority int priority, Callback callback,
-            Executor executor, String httpMethod, List<Map.Entry<String, String>> requestHeaders) {
+            Executor executor, String httpMethod, List<Map.Entry<String, String>> requestHeaders,
+            boolean disableAutoFlush) {
         mRequestContext = requestContext;
         mInitialUrl = url;
         mInitialPriority = convertStreamPriority(priority);
@@ -189,6 +210,9 @@ class CronetBidirectionalStream extends BidirectionalStream {
         mExecutor = executor;
         mInitialMethod = httpMethod;
         mRequestHeaders = stringsFromHeaderList(requestHeaders);
+        mDisableAutoFlush = disableAutoFlush;
+        mPendingData = new LinkedList<>();
+        mFlushData = new LinkedList<>();
     }
 
     @Override
@@ -199,7 +223,7 @@ class CronetBidirectionalStream extends BidirectionalStream {
             }
             try {
                 mNativeStream = nativeCreateBidirectionalStream(
-                        mRequestContext.getUrlRequestContextAdapter());
+                        mRequestContext.getUrlRequestContextAdapter(), mDisableAutoFlush);
                 mRequestContext.onRequestStarted();
                 // Non-zero startResult means an argument error.
                 int startResult = nativeStart(mNativeStream, mInitialUrl, mInitialPriority,
@@ -253,28 +277,71 @@ class CronetBidirectionalStream extends BidirectionalStream {
             if (!buffer.hasRemaining() && !endOfStream) {
                 throw new IllegalArgumentException("Empty buffer before end of stream.");
             }
-            if (mWriteState != State.WAITING_FOR_WRITE) {
-                throw new IllegalStateException("Unexpected write attempt.");
+            if (mEndOfStreamWritten) {
+                throw new IllegalArgumentException("Write after writing end of stream.");
             }
             if (isDoneLocked()) {
                 return;
             }
-            if (mOnWriteCompletedTask == null) {
-                mOnWriteCompletedTask = new OnWriteCompletedRunnable();
+            mPendingData.add(buffer);
+            if (endOfStream) {
+                mEndOfStreamWritten = true;
             }
-            mOnWriteCompletedTask.mEndOfStream = endOfStream;
-            mWriteState = State.WRITING;
-            if (!nativeWriteData(
-                        mNativeStream, buffer, buffer.position(), buffer.limit(), endOfStream)) {
-                // Still waiting on write. This is just to have consistent
-                // behavior with the other error cases.
-                mWriteState = State.WAITING_FOR_WRITE;
-                throw new IllegalArgumentException("Unable to call native write");
+            if (!mDisableAutoFlush) {
+                flushLocked();
             }
         }
     }
 
     @Override
+    public void flush() {
+        synchronized (mNativeStreamLock) {
+            flushLocked();
+        }
+    }
+
+    @SuppressWarnings("GuardedByChecker")
+    private void flushLocked() {
+        if (isDoneLocked()) {
+            return;
+        }
+        if (mPendingData.isEmpty() && mFlushData.isEmpty()) {
+            // No-op if there is nothing to write.
+            return;
+        }
+
+        // Move buffers from mPendingData to the flushing queue.
+        if (!mPendingData.isEmpty()) {
+            mFlushData.addAll(mPendingData);
+            mPendingData.clear();
+        }
+
+        if (mWriteState == State.WRITING) {
+            // If there is a write already pending, wait until onWritevCompleted is
+            // called before pushing data to the native stack.
+            return;
+        }
+        int size = mFlushData.size();
+        ByteBuffer[] buffers = new ByteBuffer[size];
+        int[] positions = new int[size];
+        int[] limits = new int[size];
+        for (int i = 0; i < size; i++) {
+            ByteBuffer buffer = mFlushData.poll();
+            buffers[i] = buffer;
+            positions[i] = buffer.position();
+            limits[i] = buffer.limit();
+        }
+        assert mFlushData.isEmpty();
+        mWriteState = State.WRITING;
+        if (!nativeWritevData(mNativeStream, buffers, positions, limits, mEndOfStreamWritten)) {
+            // Still waiting on write. This is just to have consistent
+            // behavior with the other error cases.
+            mWriteState = State.WAITING_FOR_WRITE;
+            throw new IllegalArgumentException("Unable to call native writev.");
+        }
+    }
+
+    @Override
     public void ping(PingCallback callback, Executor executor) {
         // TODO(mef): May be last thing to be implemented on Android.
         throw new UnsupportedOperationException("ping is not supported yet.");
@@ -309,9 +376,32 @@ class CronetBidirectionalStream extends BidirectionalStream {
         return mReadState != State.NOT_STARTED && mNativeStream == 0;
     }
 
+    /*
+     * Runs an onSucceeded callback if both Read and Write sides are closed.
+     */
+    private void maybeOnSucceededOnExecutor() {
+        synchronized (mNativeStreamLock) {
+            if (isDoneLocked()) {
+                return;
+            }
+            if (!(mWriteState == State.WRITING_DONE && mReadState == State.READING_DONE)) {
+                return;
+            }
+            mReadState = mWriteState = State.SUCCESS;
+            // Destroy native stream first, so UrlRequestContext could be shut
+            // down from the listener.
+            destroyNativeStreamLocked(false);
+        }
+        try {
+            mCallback.onSucceeded(CronetBidirectionalStream.this, mResponseInfo);
+        } catch (Exception e) {
+            Log.e(CronetUrlRequestContext.LOG_TAG, "Exception in onSucceeded method", e);
+        }
+    }
+
     @SuppressWarnings("unused")
     @CalledByNative
-    private void onRequestHeadersSent() {
+    private void onStreamReady() {
         postTaskToExecutor(new Runnable() {
             public void run() {
                 synchronized (mNativeStreamLock) {
@@ -320,13 +410,14 @@ class CronetBidirectionalStream extends BidirectionalStream {
                     }
                     if (doesMethodAllowWriteData(mInitialMethod)) {
                         mWriteState = State.WAITING_FOR_WRITE;
+                        mReadState = State.WAITING_FOR_READ;
                     } else {
                         mWriteState = State.WRITING_DONE;
                     }
                 }
 
                 try {
-                    mCallback.onRequestHeadersSent(CronetBidirectionalStream.this);
+                    mCallback.onStreamReady(CronetBidirectionalStream.this);
                 } catch (Exception e) {
                     onCallbackException(e);
                 }
@@ -391,18 +482,28 @@ class CronetBidirectionalStream extends BidirectionalStream {
 
     @SuppressWarnings("unused")
     @CalledByNative
-    private void onWriteCompleted(
-            final ByteBuffer byteBuffer, int initialPosition, int initialLimit) {
-        if (byteBuffer.position() != initialPosition || byteBuffer.limit() != initialLimit) {
-            failWithException(
-                    new CronetException("ByteBuffer modified externally during write", null));
-            return;
+    private void onWritevCompleted(final ByteBuffer[] byteBuffers, int[] initialPositions,
+            int[] initialLimits, boolean endOfStream) {
+        assert byteBuffers.length == initialPositions.length;
+        assert byteBuffers.length == initialLimits.length;
+        synchronized (mNativeStreamLock) {
+            mWriteState = State.WAITING_FOR_WRITE;
+            // Flush if there is anything in the flush queue mFlushData.
+            if (!mFlushData.isEmpty()) {
+                flushLocked();
+            }
+        }
+        for (int i = 0; i < byteBuffers.length; i++) {
+            ByteBuffer buffer = byteBuffers[i];
+            if (buffer.position() != initialPositions[i] || buffer.limit() != initialLimits[i]) {
+                failWithException(
+                        new CronetException("ByteBuffer modified externally during write", null));
+                return;
+            }
+            // Current implementation always writes the complete buffer.
+            buffer.position(buffer.limit());
+            postTaskToExecutor(new OnWriteCompletedRunnable(buffer, endOfStream));
         }
-        // Current implementation always writes the complete buffer.
-        byteBuffer.position(byteBuffer.limit());
-        assert mOnWriteCompletedTask.mByteBuffer == null;
-        mOnWriteCompletedTask.mByteBuffer = byteBuffer;
-        postTaskToExecutor(mOnWriteCompletedTask);
     }
 
     @SuppressWarnings("unused")
@@ -501,38 +602,6 @@ class CronetBidirectionalStream extends BidirectionalStream {
     }
 
     /**
-     * Checks whether reading and writing are done.
-     * @return false if either reading or writing is not done. If both reading and writing
-     * are done, then posts cleanup task and returns true.
-     */
-    @GuardedBy("mNativeStreamLock")
-    private boolean maybeSucceedLocked() {
-        if (mReadState != State.READING_DONE || mWriteState != State.WRITING_DONE) {
-            return false;
-        }
-
-        mReadState = mWriteState = State.SUCCESS;
-        postTaskToExecutor(new Runnable() {
-            public void run() {
-                synchronized (mNativeStreamLock) {
-                    if (isDoneLocked()) {
-                        return;
-                    }
-                    // Destroy native stream first, so UrlRequestContext could be shut
-                    // down from the listener.
-                    destroyNativeStreamLocked(false);
-                }
-                try {
-                    mCallback.onSucceeded(CronetBidirectionalStream.this, mResponseInfo);
-                } catch (Exception e) {
-                    Log.e(CronetUrlRequestContext.LOG_TAG, "Exception in onSucceeded method", e);
-                }
-            }
-        });
-        return true;
-    }
-
-    /**
      * Posts task to application Executor. Used for callbacks
      * and other tasks that should not be executed on network thread.
      */
@@ -578,7 +647,7 @@ class CronetBidirectionalStream extends BidirectionalStream {
      * Fails the stream with an exception. Only called on the Executor.
      */
     private void failWithExceptionOnExecutor(CronetException e) {
-        // Do not call into listener if request is complete.
+        // Do not call into mCallback if request is complete.
         synchronized (mNativeStreamLock) {
             if (isDoneLocked()) {
                 return;
@@ -618,7 +687,8 @@ class CronetBidirectionalStream extends BidirectionalStream {
     }
 
     // Native methods are implemented in cronet_bidirectional_stream_adapter.cc.
-    private native long nativeCreateBidirectionalStream(long urlRequestContextAdapter);
+    private native long nativeCreateBidirectionalStream(
+            long urlRequestContextAdapter, boolean disableAutoFlush);
 
     @NativeClassQualifiedName("CronetBidirectionalStreamAdapter")
     private native int nativeStart(long nativePtr, String url, int priority, String method,
@@ -629,8 +699,8 @@ class CronetBidirectionalStream extends BidirectionalStream {
             long nativePtr, ByteBuffer byteBuffer, int position, int limit);
 
     @NativeClassQualifiedName("CronetBidirectionalStreamAdapter")
-    private native boolean nativeWriteData(
-            long nativePtr, ByteBuffer byteBuffer, int position, int limit, boolean endOfStream);
+    private native boolean nativeWritevData(long nativePtr, ByteBuffer[] buffers, int[] positions,
+            int[] limits, boolean endOfStream);
 
     @NativeClassQualifiedName("CronetBidirectionalStreamAdapter")
     private native void nativeDestroy(long nativePtr, boolean sendOnCanceled);