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Retry write operation when getting ENOBUFS.

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Previously libappfuse set SO_SNDBUF to the maximum message size. However
it does not prevent ENOBUF and it made AppFusePerfTest#testReadWriteFile
flaky.

The CL let FuseBuffer retry write operation when getting ENOBUFS.

Bug: 34903085
Test: libappfuse
Change-Id: I1602474d852e1599f6e69103bcf6f18277a5644b
This commit is contained in:
Daichi Hirono 2017-03-29 13:02:30 +09:00
parent 281531bdcb
commit 6f6210dd5c
1 changed files with 30 additions and 21 deletions
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51
libappfuse/FuseBuffer.cc
View file

@ -34,6 +34,8 @@ namespace android {
namespace fuse {
namespace {
constexpr useconds_t kRetrySleepForWriting = 1000; // 1 ms
template <typename T>
bool CheckHeaderLength(const FuseMessage<T>* self, const char* name, size_t max_size) {
const auto& header = static_cast<const T*>(self)->header;
@ -91,28 +93,35 @@ ResultOrAgain WriteInternal(const FuseMessage<T>* self, int fd, int sockflag, co
const char* const buf = reinterpret_cast<const char*>(self);
const auto& header = static_cast<const T*>(self)->header;
int result;
if (sockflag) {
CHECK(data == nullptr);
result = TEMP_FAILURE_RETRY(send(fd, buf, header.len, sockflag));
} else if (data) {
const struct iovec vec[] = {{const_cast<char*>(buf), sizeof(header)},
{const_cast<void*>(data), header.len - sizeof(header)}};
result = TEMP_FAILURE_RETRY(writev(fd, vec, arraysize(vec)));
} else {
result = TEMP_FAILURE_RETRY(write(fd, buf, header.len));
}
if (result == -1) {
if (errno == EAGAIN) {
return ResultOrAgain::kAgain;
while (true) {
int result;
if (sockflag) {
CHECK(data == nullptr);
result = TEMP_FAILURE_RETRY(send(fd, buf, header.len, sockflag));
} else if (data) {
const struct iovec vec[] = {{const_cast<char*>(buf), sizeof(header)},
{const_cast<void*>(data), header.len - sizeof(header)}};
result = TEMP_FAILURE_RETRY(writev(fd, vec, arraysize(vec)));
} else {
result = TEMP_FAILURE_RETRY(write(fd, buf, header.len));
}
PLOG(ERROR) << "Failed to write a FUSE message";
return ResultOrAgain::kFailure;
if (result == -1) {
switch (errno) {
case ENOBUFS:
// When returning ENOBUFS, epoll still reports the FD is writable. Just usleep
// and retry again.
usleep(kRetrySleepForWriting);
continue;
case EAGAIN:
return ResultOrAgain::kAgain;
default:
PLOG(ERROR) << "Failed to write a FUSE message";
return ResultOrAgain::kFailure;
}
}
CHECK(static_cast<uint32_t>(result) == header.len);
return ResultOrAgain::kSuccess;
}
CHECK(static_cast<uint32_t>(result) == header.len);
return ResultOrAgain::kSuccess;
}
}
@ -161,7 +170,7 @@ bool FuseMessage<T>::Write(int fd) const {
template <typename T>
bool FuseMessage<T>::WriteWithBody(int fd, size_t max_size, const void* data) const {
CHECK(data != nullptr);
return WriteInternal<T>(this, fd, 0, data, max_size) == ResultOrAgain::kSuccess;
return WriteInternal(this, fd, 0, data, max_size) == ResultOrAgain::kSuccess;
}
template <typename T>