libui: add the Fence class

This change adds the Fence class to libui for to wrap the libsync
functionality.

Change-Id: I93a31baeee608b93c14da807a32013dabf783f84

include/ui/Fence.h

@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_FENCE_H
+#define ANDROID_FENCE_H
+
+#include <stdint.h>
+#include <limits.h>
+#include <sys/types.h>
+
+#include <ui/ANativeObjectBase.h>
+#include <ui/PixelFormat.h>
+#include <ui/Rect.h>
+#include <utils/Flattenable.h>
+#include <utils/String8.h>
+
+struct ANativeWindowBuffer;
+
+namespace android {
+
+// ===========================================================================
+// Fence
+// ===========================================================================
+
+class Fence
+    : public LightRefBase<Fence>, public Flattenable
+{
+public:
+
+    // Construct a new Fence object with an invalid file descriptor.  This
+    // should be done when the Fence object will be set up by unflattening
+    // serialized data.
+    Fence();
+
+    // Construct a new Fence object to manage a given fence file descriptor.
+    // When the new Fence object is destructed the file descriptor will be
+    // closed.
+    Fence(int fenceFd);
+
+    // wait waits for up to timeout milliseconds for the fence to signal.  If
+    // the fence signals then NO_ERROR is returned. If the timeout expires
+    // before the fence signals then -ETIME is returned.  A timeout of
+    // TIMEOUT_NEVER may be used to indicate that the call should wait
+    // indefinitely for the fence to signal.
+    int wait(unsigned int timeout);
+
+    // TIMEOUT_NEVER may be passed to the wait method to indicate that it
+    // should wait indefinitely for the fence to signal.
+    enum { TIMEOUT_NEVER = UINT_MAX };
+
+    // merge combines two Fence objects, creating a new Fence object that
+    // becomes signaled when both f1 and f2 are signaled (even if f1 or f2 is
+    // destroyed before it becomes signaled).  The name argument specifies the
+    // human-readable name to associated with the new Fence object.
+    static sp<Fence> merge(const String8& name, const sp<Fence>& f1,
+            const sp<Fence>& f2);
+
+    // Flattenable interface
+    size_t getFlattenedSize() const;
+    size_t getFdCount() const;
+    status_t flatten(void* buffer, size_t size,
+            int fds[], size_t count) const;
+    status_t unflatten(void const* buffer, size_t size,
+            int fds[], size_t count);
+
+private:
+    // Only allow instantiation using ref counting.
+    friend class LightRefBase<Fence>;
+    virtual ~Fence();
+
+    // Disallow copying
+    Fence(const Fence& rhs);
+    Fence& operator = (const Fence& rhs);
+    const Fence& operator = (const Fence& rhs) const;
+
+    int mFenceFd;
+};
+
+}; // namespace android
+
+#endif // ANDROID_FENCE_H

libs/ui/Fence.cpp

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Fence"
+#define ATRACE_TAG ATRACE_TAG_GRAPHICS
+//#define LOG_NDEBUG 0
+
+#include <sync/sync.h>
+#include <ui/Fence.h>
+#include <unistd.h>
+#include <utils/Log.h>
+#include <utils/Trace.h>
+
+namespace android {
+
+Fence::Fence() :
+    mFenceFd(-1) {
+}
+
+Fence::Fence(int fenceFd) :
+    mFenceFd(fenceFd) {
+}
+
+Fence::~Fence() {
+    if (mFenceFd != -1) {
+        close(mFenceFd);
+    }
+}
+
+int Fence::wait(unsigned int timeout) {
+    ATRACE_CALL();
+    if (mFenceFd == -1) {
+        return NO_ERROR;
+    }
+    return sync_wait(mFenceFd, timeout);
+}
+
+sp<Fence> Fence::merge(const String8& name, const sp<Fence>& f1,
+        const sp<Fence>& f2) {
+    ATRACE_CALL();
+    int result = sync_merge(name.string(), f1->mFenceFd, f2->mFenceFd);
+    if (result == -1) {
+        ALOGE("merge: sync_merge returned an error: %s (%d)", strerror(-errno),
+                errno);
+        return sp<Fence>();
+    }
+    return sp<Fence>(new Fence(result));
+}
+
+size_t Fence::getFlattenedSize() const {
+    return 0;
+}
+
+size_t Fence::getFdCount() const {
+    return 1;
+}
+
+status_t Fence::flatten(void* buffer, size_t size, int fds[],
+        size_t count) const {
+    if (size != 0 || count != 1) {
+        return BAD_VALUE;
+    }
+
+    fds[0] = mFenceFd;
+    return NO_ERROR;
+}
+
+status_t Fence::unflatten(void const* buffer, size_t size, int fds[],
+        size_t count) {
+    if (size != 0 || count != 1) {
+        return BAD_VALUE;
+    }
+    if (mFenceFd != -1) {
+        // Don't unflatten if we already have a valid fd.
+        return INVALID_OPERATION;
+    }
+
+    mFenceFd = fds[0];
+    return NO_ERROR;
+}
+
+} // namespace android