6c4febee29
This implements a memory monitor for macOS, Linux and Windows. It registers a callback that invokes `SBDebugger::MemoryPressureDetected` when a low memory event is detected. This is motivated by the new server mode, where the lldb-dap process will live across multiple debug sessions and will use more memory due to caching.
110 lines
2.8 KiB
C++
110 lines
2.8 KiB
C++
//===-- MemoryMonitor.cpp -------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "lldb/Host/MemoryMonitor.h"
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#include "lldb/Host/HostThread.h"
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#include "lldb/Host/ThreadLauncher.h"
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#include "lldb/Utility/LLDBLog.h"
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#include "lldb/Utility/Log.h"
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#include "llvm/ADT/ScopeExit.h"
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#include "llvm/Support/Error.h"
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#include <atomic>
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#include <cstddef>
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#include <cstdio>
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#include <cstring>
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#if defined(__linux__)
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#include <fcntl.h>
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#include <poll.h>
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#include <unistd.h>
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#endif
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#if defined(_WIN32)
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#include <windows.h>
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#endif
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using namespace lldb_private;
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class MemoryMonitorPoll : public MemoryMonitor {
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public:
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using MemoryMonitor::MemoryMonitor;
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lldb::thread_result_t MonitorThread() {
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#if defined(__linux__)
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struct pollfd fds;
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fds.fd = open("/proc/pressure/memory", O_RDWR | O_NONBLOCK);
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if (fds.fd < 0)
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return {};
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fds.events = POLLPRI;
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auto cleanup = llvm::make_scope_exit([&]() { close(fds.fd); });
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// Detect a 50ms stall in a 2 second time window.
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const char trig[] = "some 50000 2000000";
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if (write(fds.fd, trig, strlen(trig) + 1) < 0)
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return {};
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while (!m_done) {
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int n = poll(&fds, 1, g_timeout);
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if (n > 0) {
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if (fds.revents & POLLERR)
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return {};
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if (fds.revents & POLLPRI)
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m_callback();
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}
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}
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#endif
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#if defined(_WIN32)
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HANDLE low_memory_notification =
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CreateMemoryResourceNotification(LowMemoryResourceNotification);
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if (!low_memory_notification)
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return {};
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while (!m_done) {
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if (WaitForSingleObject(low_memory_notification, g_timeout) ==
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WAIT_OBJECT_0) {
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m_callback();
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}
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}
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#endif
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return {};
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}
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void Start() override {
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llvm::Expected<HostThread> memory_monitor_thread =
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ThreadLauncher::LaunchThread("lldb.debugger.memory-monitor",
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[this] { return MonitorThread(); });
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if (memory_monitor_thread) {
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m_memory_monitor_thread = *memory_monitor_thread;
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} else {
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LLDB_LOG_ERROR(GetLog(LLDBLog::Host), memory_monitor_thread.takeError(),
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"failed to launch host thread: {0}");
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}
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}
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void Stop() override {
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if (m_memory_monitor_thread.IsJoinable()) {
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m_done = true;
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m_memory_monitor_thread.Join(nullptr);
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}
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}
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private:
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static constexpr uint32_t g_timeout = 1000;
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std::atomic<bool> m_done = false;
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HostThread m_memory_monitor_thread;
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};
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#if !defined(__APPLE__)
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std::unique_ptr<MemoryMonitor> MemoryMonitor::Create(Callback callback) {
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return std::make_unique<MemoryMonitorPoll>(callback);
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}
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#endif
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