Add BufferReleaseChannel
BufferReleaseChannel will be used to communicate buffer releases from SurfaceFlinger to BLASTBufferQueue.
Bug: 294133380
Flag: com.android.graphics.libgui.flags.buffer_release_channel
Test: BufferReleaseChannelTest
Change-Id: Ic38e8eefc96abc0b2bbe780115b7628413e8b829
diff --git a/libs/gui/BufferReleaseChannel.cpp b/libs/gui/BufferReleaseChannel.cpp
new file mode 100644
index 0000000..27367aa
--- /dev/null
+++ b/libs/gui/BufferReleaseChannel.cpp
@@ -0,0 +1,358 @@
+/*
+ * Copyright (C) 2024 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 "BufferReleaseChannel"
+
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+
+#include <android-base/result.h>
+#include <android/binder_status.h>
+#include <binder/Parcel.h>
+#include <utils/Flattenable.h>
+
+#include <gui/BufferReleaseChannel.h>
+#include <private/gui/ParcelUtils.h>
+
+using android::base::Result;
+
+namespace android::gui {
+
+namespace {
+
+template <typename T>
+static void readAligned(const void*& buffer, size_t& size, T& value) {
+ size -= FlattenableUtils::align<alignof(T)>(buffer);
+ FlattenableUtils::read(buffer, size, value);
+}
+
+template <typename T>
+static void writeAligned(void*& buffer, size_t& size, T value) {
+ size -= FlattenableUtils::align<alignof(T)>(buffer);
+ FlattenableUtils::write(buffer, size, value);
+}
+
+template <typename T>
+static void addAligned(size_t& size, T /* value */) {
+ size = FlattenableUtils::align<sizeof(T)>(size);
+ size += sizeof(T);
+}
+
+template <typename T>
+static inline constexpr uint32_t low32(const T n) {
+ return static_cast<uint32_t>(static_cast<uint64_t>(n));
+}
+
+template <typename T>
+static inline constexpr uint32_t high32(const T n) {
+ return static_cast<uint32_t>(static_cast<uint64_t>(n) >> 32);
+}
+
+template <typename T>
+static inline constexpr T to64(const uint32_t lo, const uint32_t hi) {
+ return static_cast<T>(static_cast<uint64_t>(hi) << 32 | lo);
+}
+
+} // namespace
+
+size_t BufferReleaseChannel::Message::getPodSize() const {
+ size_t size = 0;
+ addAligned(size, low32(releaseCallbackId.bufferId));
+ addAligned(size, high32(releaseCallbackId.bufferId));
+ addAligned(size, low32(releaseCallbackId.framenumber));
+ addAligned(size, high32(releaseCallbackId.framenumber));
+ addAligned(size, maxAcquiredBufferCount);
+ return size;
+}
+
+size_t BufferReleaseChannel::Message::getFlattenedSize() const {
+ size_t size = releaseFence->getFlattenedSize();
+ size = FlattenableUtils::align<4>(size);
+ size += getPodSize();
+ return size;
+}
+
+status_t BufferReleaseChannel::Message::flatten(void*& buffer, size_t& size, int*& fds,
+ size_t& count) const {
+ if (status_t err = releaseFence->flatten(buffer, size, fds, count); err != OK) {
+ return err;
+ }
+ size -= FlattenableUtils::align<4>(buffer);
+
+ // Check we still have enough space
+ if (size < getPodSize()) {
+ return NO_MEMORY;
+ }
+
+ writeAligned(buffer, size, low32(releaseCallbackId.bufferId));
+ writeAligned(buffer, size, high32(releaseCallbackId.bufferId));
+ writeAligned(buffer, size, low32(releaseCallbackId.framenumber));
+ writeAligned(buffer, size, high32(releaseCallbackId.framenumber));
+ writeAligned(buffer, size, maxAcquiredBufferCount);
+ return OK;
+}
+
+status_t BufferReleaseChannel::Message::unflatten(void const*& buffer, size_t& size,
+ int const*& fds, size_t& count) {
+ releaseFence = new Fence();
+ if (status_t err = releaseFence->unflatten(buffer, size, fds, count); err != OK) {
+ return err;
+ }
+ size -= FlattenableUtils::align<4>(buffer);
+
+ // Check we still have enough space
+ if (size < getPodSize()) {
+ return OK;
+ }
+
+ uint32_t bufferIdLo = 0, bufferIdHi = 0;
+ uint32_t frameNumberLo = 0, frameNumberHi = 0;
+
+ readAligned(buffer, size, bufferIdLo);
+ readAligned(buffer, size, bufferIdHi);
+ releaseCallbackId.bufferId = to64<int64_t>(bufferIdLo, bufferIdHi);
+ readAligned(buffer, size, frameNumberLo);
+ readAligned(buffer, size, frameNumberHi);
+ releaseCallbackId.framenumber = to64<uint64_t>(frameNumberLo, frameNumberHi);
+ readAligned(buffer, size, maxAcquiredBufferCount);
+
+ return OK;
+}
+
+status_t BufferReleaseChannel::ConsumerEndpoint::readReleaseFence(
+ ReleaseCallbackId& outReleaseCallbackId, sp<Fence>& outReleaseFence,
+ uint32_t& outMaxAcquiredBufferCount) {
+ Message message;
+ mFlattenedBuffer.resize(message.getFlattenedSize());
+ std::array<uint8_t, CMSG_SPACE(sizeof(int))> controlMessageBuffer;
+
+ iovec iov{
+ .iov_base = mFlattenedBuffer.data(),
+ .iov_len = mFlattenedBuffer.size(),
+ };
+
+ msghdr msg{
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = controlMessageBuffer.data(),
+ .msg_controllen = controlMessageBuffer.size(),
+ };
+
+ int result;
+ do {
+ result = recvmsg(mFd, &msg, 0);
+ } while (result == -1 && errno == EINTR);
+ if (result == -1) {
+ if (errno == EWOULDBLOCK || errno == EAGAIN) {
+ return WOULD_BLOCK;
+ }
+ ALOGE("Error reading release fence from socket: error %#x (%s)", errno, strerror(errno));
+ return UNKNOWN_ERROR;
+ }
+
+ if (msg.msg_iovlen != 1) {
+ ALOGE("Error reading release fence from socket: bad data length");
+ return UNKNOWN_ERROR;
+ }
+
+ if (msg.msg_controllen % sizeof(int) != 0) {
+ ALOGE("Error reading release fence from socket: bad fd length");
+ return UNKNOWN_ERROR;
+ }
+
+ size_t dataLen = msg.msg_iov->iov_len;
+ const void* data = static_cast<const void*>(msg.msg_iov->iov_base);
+ if (!data) {
+ ALOGE("Error reading release fence from socket: no buffer data");
+ return UNKNOWN_ERROR;
+ }
+
+ size_t fdCount = 0;
+ const int* fdData = nullptr;
+ if (cmsghdr* cmsg = CMSG_FIRSTHDR(&msg)) {
+ fdData = reinterpret_cast<const int*>(CMSG_DATA(cmsg));
+ fdCount = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
+ }
+
+ if (status_t err = message.unflatten(data, dataLen, fdData, fdCount); err != OK) {
+ return err;
+ }
+
+ outReleaseCallbackId = message.releaseCallbackId;
+ outReleaseFence = std::move(message.releaseFence);
+ outMaxAcquiredBufferCount = message.maxAcquiredBufferCount;
+
+ return OK;
+}
+
+int BufferReleaseChannel::ProducerEndpoint::writeReleaseFence(const ReleaseCallbackId& callbackId,
+ const sp<Fence>& fence,
+ uint32_t maxAcquiredBufferCount) {
+ Message message{callbackId, fence ? fence : Fence::NO_FENCE, maxAcquiredBufferCount};
+ mFlattenedBuffer.resize(message.getFlattenedSize());
+ int flattenedFd;
+ {
+ // Make copies of needed items since flatten modifies them, and we don't
+ // want to send anything if there's an error during flatten.
+ void* flattenedBufferPtr = mFlattenedBuffer.data();
+ size_t flattenedBufferSize = mFlattenedBuffer.size();
+ int* flattenedFdPtr = &flattenedFd;
+ size_t flattenedFdCount = 1;
+ if (status_t err = message.flatten(flattenedBufferPtr, flattenedBufferSize, flattenedFdPtr,
+ flattenedFdCount);
+ err != OK) {
+ ALOGE("Failed to flatten BufferReleaseChannel message.");
+ return err;
+ }
+ }
+
+ iovec iov{
+ .iov_base = mFlattenedBuffer.data(),
+ .iov_len = mFlattenedBuffer.size(),
+ };
+
+ msghdr msg{
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ };
+
+ std::array<uint8_t, CMSG_SPACE(sizeof(int))> controlMessageBuffer;
+ if (fence && fence->isValid()) {
+ msg.msg_control = controlMessageBuffer.data();
+ msg.msg_controllen = controlMessageBuffer.size();
+
+ cmsghdr* cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+ memcpy(CMSG_DATA(cmsg), &flattenedFd, sizeof(int));
+ }
+
+ int result;
+ do {
+ result = sendmsg(mFd, &msg, 0);
+ } while (result == -1 && errno == EINTR);
+ if (result == -1) {
+ ALOGD("Error writing release fence to socket: error %#x (%s)", errno, strerror(errno));
+ return -errno;
+ }
+
+ return OK;
+}
+
+status_t BufferReleaseChannel::ProducerEndpoint::readFromParcel(const android::Parcel* parcel) {
+ if (!parcel) return STATUS_BAD_VALUE;
+ SAFE_PARCEL(parcel->readUtf8FromUtf16, &mName);
+ SAFE_PARCEL(parcel->readUniqueFileDescriptor, &mFd);
+ return STATUS_OK;
+}
+
+status_t BufferReleaseChannel::ProducerEndpoint::writeToParcel(android::Parcel* parcel) const {
+ if (!parcel) return STATUS_BAD_VALUE;
+ SAFE_PARCEL(parcel->writeUtf8AsUtf16, mName);
+ SAFE_PARCEL(parcel->writeUniqueFileDescriptor, mFd);
+ return STATUS_OK;
+}
+
+status_t BufferReleaseChannel::open(std::string name,
+ std::unique_ptr<ConsumerEndpoint>& outConsumer,
+ std::shared_ptr<ProducerEndpoint>& outProducer) {
+ outConsumer.reset();
+ outProducer.reset();
+
+ int sockets[2];
+ if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sockets)) {
+ ALOGE("[%s] Failed to create socket pair. errorno=%d message='%s'", name.c_str(), errno,
+ strerror(errno));
+ return -errno;
+ }
+
+ android::base::unique_fd consumerFd(sockets[0]);
+ android::base::unique_fd producerFd(sockets[1]);
+
+ // Socket buffer size. The default is typically about 128KB, which is much larger than
+ // we really need.
+ size_t bufferSize = 32 * 1024;
+ if (setsockopt(consumerFd.get(), SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize)) ==
+ -1) {
+ ALOGE("[%s] Failed to set consumer socket send buffer size. errno=%d message='%s'",
+ name.c_str(), errno, strerror(errno));
+ return -errno;
+ }
+ if (setsockopt(consumerFd.get(), SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize)) ==
+ -1) {
+ ALOGE("[%s] Failed to set consumer socket receive buffer size. errno=%d "
+ "message='%s'",
+ name.c_str(), errno, strerror(errno));
+ return -errno;
+ }
+ if (setsockopt(producerFd.get(), SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize)) ==
+ -1) {
+ ALOGE("[%s] Failed to set producer socket send buffer size. errno=%d message='%s'",
+ name.c_str(), errno, strerror(errno));
+ return -errno;
+ }
+ if (setsockopt(producerFd.get(), SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize)) ==
+ -1) {
+ ALOGE("[%s] Failed to set producer socket receive buffer size. errno=%d "
+ "message='%s'",
+ name.c_str(), errno, strerror(errno));
+ return -errno;
+ }
+
+ // Configure the consumer socket to be non-blocking.
+ int flags = fcntl(consumerFd.get(), F_GETFL, 0);
+ if (flags == -1) {
+ ALOGE("[%s] Failed to get consumer socket flags. errno=%d message='%s'", name.c_str(),
+ errno, strerror(errno));
+ return -errno;
+ }
+ if (fcntl(consumerFd.get(), F_SETFL, flags | O_NONBLOCK) == -1) {
+ ALOGE("[%s] Failed to set consumer socket to non-blocking mode. errno=%d "
+ "message='%s'",
+ name.c_str(), errno, strerror(errno));
+ return -errno;
+ }
+
+ // Configure a timeout for the producer socket.
+ const timeval timeout{.tv_sec = 1, .tv_usec = 0};
+ if (setsockopt(producerFd.get(), SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeval)) == -1) {
+ ALOGE("[%s] Failed to set producer socket timeout. errno=%d message='%s'", name.c_str(),
+ errno, strerror(errno));
+ return -errno;
+ }
+
+ // Make the consumer read-only
+ if (shutdown(consumerFd.get(), SHUT_WR) == -1) {
+ ALOGE("[%s] Failed to shutdown writing on consumer socket. errno=%d message='%s'",
+ name.c_str(), errno, strerror(errno));
+ return -errno;
+ }
+
+ // Make the producer write-only
+ if (shutdown(producerFd.get(), SHUT_RD) == -1) {
+ ALOGE("[%s] Failed to shutdown reading on producer socket. errno=%d message='%s'",
+ name.c_str(), errno, strerror(errno));
+ return -errno;
+ }
+
+ outConsumer = std::make_unique<ConsumerEndpoint>(name, std::move(consumerFd));
+ outProducer = std::make_shared<ProducerEndpoint>(std::move(name), std::move(producerFd));
+ return STATUS_OK;
+}
+
+} // namespace android::gui
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