foxyzandClaude Opus 5.5
d002ff6941
Hot restart frees the old isolate's NativeCallables while mpv handles stay alive; media_kit then quits them on the next start and mpv calls the dead wakeup callback (SIGSEGV on the mpv 'core' thread). A debug-only runner hook clears every live handle's wakeup callback on the engine's on-pre-engine-restart signal. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
70 lines
2.4 KiB
C++
70 lines
2.4 KiB
C++
#include "hot_restart_guard.h"
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#ifdef NDEBUG
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void hot_restart_guard_attach(FlView* view) {}
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#else
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#include <dlfcn.h>
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#include <stdint.h>
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#include <unistd.h>
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namespace {
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// Mirrors media_kit's NativeReferenceHolder (debug only): a calloc'd buffer
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// of kReferenceBufferSize intptr slots holding live mpv_handle addresses,
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// its address written in decimal to <tmp>/<kFilePrefix><pid>.
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constexpr int kReferenceBufferSize = 512;
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constexpr char kFilePrefix[] = "com.alexmercerind.media_kit.NativeReferenceHolder.";
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using SetWakeupCallback = void (*)(void* ctx, void (*cb)(void*), void* d);
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SetWakeupCallback find_set_wakeup_callback() {
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static const char* const kNames[] = {"libmpv.so.2", "libmpv.so", "libmpv.so.1"};
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for (const char* name : kNames) {
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void* lib = dlopen(name, RTLD_NOW | RTLD_NOLOAD);
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if (lib == nullptr) continue;
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auto fn = reinterpret_cast<SetWakeupCallback>(
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dlsym(lib, "mpv_set_wakeup_callback"));
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dlclose(lib); // Drops only the reference NOLOAD added.
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if (fn != nullptr) return fn;
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}
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return nullptr;
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}
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// Runs on the engine's UI thread before the old isolate shuts down, so the
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// buffer is not being written concurrently. Clearing the callback takes the
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// same lock mpv calls it under: once this returns, mpv never calls it again.
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// The handles stay in the buffer: media_kit's startup in the new isolate
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// still sends them "quit".
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void on_pre_engine_restart(FlEngine* engine, gpointer user_data) {
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g_autofree gchar* name = g_strdup_printf("%s%d", kFilePrefix, getpid());
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g_autofree gchar* path = g_build_filename(g_get_tmp_dir(), name, nullptr);
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g_autofree gchar* contents = nullptr;
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if (!g_file_get_contents(path, &contents, nullptr, nullptr)) return;
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const guint64 address = g_ascii_strtoull(contents, nullptr, 10);
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if (address == 0) return;
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const SetWakeupCallback set_wakeup = find_set_wakeup_callback();
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if (set_wakeup == nullptr) return;
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const auto* slots = reinterpret_cast<const intptr_t*>(address);
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int cleared = 0;
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for (int i = 0; i < kReferenceBufferSize; i++) {
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if (slots[i] == 0) continue;
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set_wakeup(reinterpret_cast<void*>(slots[i]), nullptr, nullptr);
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cleared++;
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}
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if (cleared > 0) {
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g_message("hot restart: unhooked %d mpv wakeup callback(s)", cleared);
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}
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}
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} // namespace
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void hot_restart_guard_attach(FlView* view) {
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g_signal_connect(fl_view_get_engine(view), "on-pre-engine-restart",
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G_CALLBACK(on_pre_engine_restart), nullptr);
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}
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#endif
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