[Lldb-commits] [lldb] [lldb-dap] Implement a MemoryMonitor (PR #129332)

[Walter Erquinigo via lldb-commits]

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@@ -0,0 +1,110 @@
+//===-- MemoryMonitor.cpp -------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/Host/MemoryMonitor.h"
+#include "lldb/Host/HostThread.h"
+#include "lldb/Host/ThreadLauncher.h"
+#include "lldb/Utility/LLDBLog.h"
+#include "lldb/Utility/Log.h"
+#include "llvm/ADT/ScopeExit.h"
+#include "llvm/Support/Error.h"
+#include <atomic>
+#include <cstddef>
+#include <cstdio>
+#include <cstring>
+
+#if defined(__linux__)
+#include <fcntl.h>
+#include <poll.h>
+#include <unistd.h>
+#endif
+
+#if defined(_WIN32)
+#include <memoryapi.h>
+#include <synchapi.h>
+#endif
+
+using namespace lldb_private;
+
+class MemoryMonitorPoll : public MemoryMonitor {
+public:
+  using MemoryMonitor::MemoryMonitor;
+
+  lldb::thread_result_t MonitorThread() {
+#if defined(__linux__)
+    struct pollfd fds;
+    fds.fd = open("/proc/pressure/memory", O_RDWR | O_NONBLOCK);
+    if (fds.fd < 0)
+      return {};
+    fds.events = POLLPRI;
+
+    auto cleanup = llvm::make_scope_exit([&]() { close(fds.fd); });
+
+    // Detect a 50ms stall in a 2 second time window.
+    const char trig[] = "some 50000 2000000";
+    if (write(fds.fd, trig, strlen(trig) + 1) < 0)
+      return {};
+
+    while (!m_done) {
+      int n = poll(&fds, 1, g_timeout);
+      if (n > 0) {
+        if (fds.revents & POLLERR)
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walter-erquinigo wrote:

if there's an error, is there a way to restart the loop?

https://github.com/llvm/llvm-project/pull/129332