augusto2112 updated this revision to Diff 549539.
augusto2112 added a comment.
Update to two shared mutexes
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D157654/new/
https://reviews.llvm.org/D157654
Files:
lldb/include/lldb/Host/posix/PipePosix.h
lldb/source/Host/posix/PipePosix.cpp
Index: lldb/source/Host/posix/PipePosix.cpp
===================================================================
--- lldb/source/Host/posix/PipePosix.cpp
+++ lldb/source/Host/posix/PipePosix.cpp
@@ -65,16 +65,21 @@
pipe_posix.ReleaseWriteFileDescriptor()} {}
PipePosix &PipePosix::operator=(PipePosix &&pipe_posix) {
+ std::scoped_lock guard(m_read_mutex, m_write_mutex, pipe_posix.m_read_mutex,
+ pipe_posix.m_write_mutex);
+
PipeBase::operator=(std::move(pipe_posix));
- m_fds[READ] = pipe_posix.ReleaseReadFileDescriptor();
- m_fds[WRITE] = pipe_posix.ReleaseWriteFileDescriptor();
+ m_fds[READ] = pipe_posix.ReleaseReadFileDescriptorUnlocked();
+ m_fds[WRITE] = pipe_posix.ReleaseWriteFileDescriptorUnlocked();
return *this;
}
PipePosix::~PipePosix() { Close(); }
Status PipePosix::CreateNew(bool child_processes_inherit) {
- if (CanRead() || CanWrite())
+ // Lock both mutexes in exclusive mode.
+ std::scoped_lock guard(m_read_mutex, m_write_mutex);
+ if (CanReadUnlocked() || CanWriteUnlocked())
return Status(EINVAL, eErrorTypePOSIX);
Status error;
@@ -87,7 +92,7 @@
if (!child_processes_inherit) {
if (!SetCloexecFlag(m_fds[0]) || !SetCloexecFlag(m_fds[1])) {
error.SetErrorToErrno();
- Close();
+ CloseUnlocked();
return error;
}
}
@@ -103,7 +108,11 @@
}
Status PipePosix::CreateNew(llvm::StringRef name, bool child_process_inherit) {
- if (CanRead() || CanWrite())
+ // Lock both mutexes in shared mode.
+ std::shared_lock read_guard(m_read_mutex, std::defer_lock);
+ std::shared_lock write_guard(m_write_mutex, std::defer_lock);
+ std::lock(read_guard, write_guard);
+ if (CanReadUnlocked() || CanWriteUnlocked())
return Status("Pipe is already opened");
Status error;
@@ -140,7 +149,13 @@
Status PipePosix::OpenAsReader(llvm::StringRef name,
bool child_process_inherit) {
- if (CanRead() || CanWrite())
+ // Lock read mutex in exclusive mode and write mutex in shared mode, since we
+ // only write the read file descriptor.
+ std::unique_lock read_guard(m_read_mutex, std::defer_lock);
+ std::shared_lock write_guard(m_write_mutex, std::defer_lock);
+ std::lock(read_guard, write_guard);
+
+ if (CanReadUnlocked() || CanWriteUnlocked())
return Status("Pipe is already opened");
int flags = O_RDONLY | O_NONBLOCK;
@@ -161,7 +176,8 @@
PipePosix::OpenAsWriterWithTimeout(llvm::StringRef name,
bool child_process_inherit,
const std::chrono::microseconds &timeout) {
- if (CanRead() || CanWrite())
+ std::unique_lock guard(m_write_mutex);
+ if (CanReadUnlocked() || CanWriteUnlocked())
return Status("Pipe is already opened");
int flags = O_WRONLY | O_NONBLOCK;
@@ -171,7 +187,7 @@
using namespace std::chrono;
const auto finish_time = Now() + timeout;
- while (!CanWrite()) {
+ while (!CanWriteUnlocked()) {
if (timeout != microseconds::zero()) {
const auto dur = duration_cast<microseconds>(finish_time - Now()).count();
if (dur <= 0)
@@ -196,25 +212,54 @@
return Status();
}
-int PipePosix::GetReadFileDescriptor() const { return m_fds[READ]; }
+int PipePosix::GetReadFileDescriptor() const {
+ std::shared_lock guad(m_read_mutex);
+ return GetReadFileDescriptorUnlocked();
+}
+
+int PipePosix::GetReadFileDescriptorUnlocked() const {
+ return m_fds[READ];
+}
-int PipePosix::GetWriteFileDescriptor() const { return m_fds[WRITE]; }
+int PipePosix::GetWriteFileDescriptor() const {
+ std::shared_lock guard(m_write_mutex);
+ return GetWriteFileDescriptorUnlocked();
+}
+
+int PipePosix::GetWriteFileDescriptorUnlocked() const {
+ return m_fds[WRITE];
+}
int PipePosix::ReleaseReadFileDescriptor() {
+ std::unique_lock guard(m_read_mutex);
+ return ReleaseReadFileDescriptorUnlocked();
+}
+
+int PipePosix::ReleaseReadFileDescriptorUnlocked() {
const int fd = m_fds[READ];
m_fds[READ] = PipePosix::kInvalidDescriptor;
return fd;
}
int PipePosix::ReleaseWriteFileDescriptor() {
+ std::unique_lock guard(m_write_mutex);
+ return ReleaseWriteFileDescriptorUnlocked();
+}
+
+int PipePosix::ReleaseWriteFileDescriptorUnlocked() {
const int fd = m_fds[WRITE];
m_fds[WRITE] = PipePosix::kInvalidDescriptor;
return fd;
}
void PipePosix::Close() {
- CloseReadFileDescriptor();
- CloseWriteFileDescriptor();
+ std::scoped_lock guard(m_read_mutex, m_write_mutex);
+ CloseUnlocked();
+}
+
+void PipePosix::CloseUnlocked() {
+ CloseReadFileDescriptorUnlocked();
+ CloseWriteFileDescriptorUnlocked();
}
Status PipePosix::Delete(llvm::StringRef name) {
@@ -222,22 +267,41 @@
}
bool PipePosix::CanRead() const {
+ std::shared_lock guard(m_read_mutex);
+ return CanReadUnlocked();
+}
+
+bool PipePosix::CanReadUnlocked() const {
return m_fds[READ] != PipePosix::kInvalidDescriptor;
}
bool PipePosix::CanWrite() const {
+ std::shared_lock guard(m_write_mutex);
+ return CanWriteUnlocked();
+}
+
+bool PipePosix::CanWriteUnlocked() const {
return m_fds[WRITE] != PipePosix::kInvalidDescriptor;
}
void PipePosix::CloseReadFileDescriptor() {
- if (CanRead()) {
+ std::unique_lock guard(m_read_mutex);
+ CloseReadFileDescriptorUnlocked();
+}
+void PipePosix::CloseReadFileDescriptorUnlocked() {
+ if (CanReadUnlocked()) {
close(m_fds[READ]);
m_fds[READ] = PipePosix::kInvalidDescriptor;
}
}
void PipePosix::CloseWriteFileDescriptor() {
- if (CanWrite()) {
+ std::unique_lock guard(m_write_mutex);
+ CloseWriteFileDescriptorUnlocked();
+}
+
+void PipePosix::CloseWriteFileDescriptorUnlocked() {
+ if (CanWriteUnlocked()) {
close(m_fds[WRITE]);
m_fds[WRITE] = PipePosix::kInvalidDescriptor;
}
@@ -246,11 +310,12 @@
Status PipePosix::ReadWithTimeout(void *buf, size_t size,
const std::chrono::microseconds &timeout,
size_t &bytes_read) {
+ std::shared_lock guard(m_read_mutex);
bytes_read = 0;
- if (!CanRead())
+ if (!CanReadUnlocked())
return Status(EINVAL, eErrorTypePOSIX);
- const int fd = GetReadFileDescriptor();
+ const int fd = GetReadFileDescriptorUnlocked();
SelectHelper select_helper;
select_helper.SetTimeout(timeout);
@@ -278,11 +343,12 @@
}
Status PipePosix::Write(const void *buf, size_t size, size_t &bytes_written) {
+ std::shared_lock guard(m_write_mutex);
bytes_written = 0;
- if (!CanWrite())
+ if (!CanWriteUnlocked())
return Status(EINVAL, eErrorTypePOSIX);
- const int fd = GetWriteFileDescriptor();
+ const int fd = GetWriteFileDescriptorUnlocked();
SelectHelper select_helper;
select_helper.SetTimeout(std::chrono::seconds(0));
select_helper.FDSetWrite(fd);
Index: lldb/include/lldb/Host/posix/PipePosix.h
===================================================================
--- lldb/include/lldb/Host/posix/PipePosix.h
+++ lldb/include/lldb/Host/posix/PipePosix.h
@@ -9,8 +9,8 @@
#ifndef LLDB_HOST_POSIX_PIPEPOSIX_H
#define LLDB_HOST_POSIX_PIPEPOSIX_H
#if defined(__cplusplus)
-
#include "lldb/Host/PipeBase.h"
+#include <shared_mutex>
namespace lldb_private {
@@ -71,7 +71,22 @@
size_t &bytes_read) override;
private:
+ bool CanReadUnlocked() const;
+ bool CanWriteUnlocked() const;
+
+ int GetReadFileDescriptorUnlocked() const;
+ int GetWriteFileDescriptorUnlocked() const;
+ int ReleaseReadFileDescriptorUnlocked();
+ int ReleaseWriteFileDescriptorUnlocked();
+ void CloseReadFileDescriptorUnlocked();
+ void CloseWriteFileDescriptorUnlocked();
+ void CloseUnlocked();
+
int m_fds[2];
+
+ /// Locks for m_fds;
+ mutable std::shared_mutex m_read_mutex;
+ mutable std::shared_mutex m_write_mutex;
};
} // namespace lldb_private
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