diff options
Diffstat (limited to 'cbits')
| -rw-r--r-- | cbits/hook.c | 151 |
1 files changed, 124 insertions, 27 deletions
diff --git a/cbits/hook.c b/cbits/hook.c index 2175be4..d8619ff 100644 --- a/cbits/hook.c +++ b/cbits/hook.c @@ -100,8 +100,14 @@ static void shadow_copy(struct ShadowDetails *dst, const struct GCDetails_ *src) // GLOBAL VARIABLES // -------- +static bool constructor_worked = false; +static bool hook_initialised = false; +static bool logging_enabled = false; +static void (*hook_c_delegate)(const struct GCDetails_*) = NULL; + +static mtx_t state_mutex; + static void (*old_hook)(const struct GCDetails_ *details) = NULL; -static mtx_t detlog_mutex; static size_t detlog_capacity = 0, detlog_length = 0; static struct ShadowDetails *detlog = NULL; @@ -116,13 +122,13 @@ static void hook_callback(const struct GCDetails_ *details) { // Do this now already, before waiting on the mutex struct timespec now; - if (clock_gettime(CLOCK_MONOTONIC, &now) != 0) { + if (logging_enabled && clock_gettime(CLOCK_MONOTONIC, &now) != 0) { perror("clock_gettime"); fatal_failure = true; goto cleanup_no_mutex; } - if (mtx_lock(&detlog_mutex) != thrd_success) { + if (mtx_lock(&state_mutex) != thrd_success) { fprintf(stderr, "ghc-gc-hook: ERROR: Mutex lock failed\n"); fatal_failure = true; goto cleanup_no_mutex; @@ -130,62 +136,153 @@ static void hook_callback(const struct GCDetails_ *details) { // mutex is locked from here - if (detlog_length == detlog_capacity) { - detlog_capacity = detlog_capacity == 0 ? 128 : 2 * detlog_capacity; - detlog = realloc(detlog, detlog_capacity * sizeof(detlog[0])); - if (detlog == NULL || detlog_capacity == 0) { // also check for overflow here - fprintf(stderr, "ghc-gc-hook: ERROR: Could not allocate memory for GC log hook\n"); - fatal_failure = true; - goto cleanup; + if (logging_enabled) { + if (detlog_length == detlog_capacity) { + detlog_capacity = detlog_capacity == 0 ? 128 : 2 * detlog_capacity; + detlog = realloc(detlog, detlog_capacity * sizeof(detlog[0])); + if (detlog == NULL || detlog_capacity == 0) { // also check for overflow here + fprintf(stderr, "ghc-gc-hook: ERROR: Could not allocate memory for GC log hook\n"); + fatal_failure = true; + goto cleanup; + } } + + struct ShadowDetails *dst = &detlog[detlog_length]; + dst->timestamp_sec = now.tv_sec; + dst->timestamp_nsec = now.tv_nsec; + shadow_copy(dst, details); + detlog_length++; } - struct ShadowDetails *dst = &detlog[detlog_length]; - dst->timestamp_sec = now.tv_sec; - dst->timestamp_nsec = now.tv_nsec; - shadow_copy(dst, details); - detlog_length++; + if (hook_c_delegate) hook_c_delegate(details); cleanup: - mtx_unlock(&detlog_mutex); // ignore return value + mtx_unlock(&state_mutex); // ignore return value cleanup_no_mutex: if (old_hook) old_hook(details); } +__attribute__((constructor)) +static void constructor(void) { + if (mtx_init(&state_mutex, mtx_plain) != thrd_success) { + fprintf(stderr, "ghc-gc-hook: ERROR: Mutex initialisation failed\n"); + return; + } + + constructor_worked = true; +} + // -------- // EXPORTED FUNCTIONS // -------- +// Only works if logging is enabled. void copy_log_to_buffer(size_t space_available, char *buffer, size_t *unit_size, size_t *num_stored) { - if (mtx_lock(&detlog_mutex) != thrd_success) { + *unit_size = sizeof(detlog[0]); + + if (mtx_lock(&state_mutex) != thrd_success) { fprintf(stderr, "ghc-gc-hook: ERROR: Mutex lock failed\n"); - *unit_size = 0; *num_stored = 0; return; } - const size_t sz = sizeof(detlog[0]); - const size_t n = min_sz(space_available / sz, detlog_length); + if (detlog_length == 0) { + *num_stored = 0; + goto unlock_return; + } + + const size_t n = min_sz(space_available / sizeof(detlog[0]), detlog_length); // First copy over the fitting items - memcpy(buffer, detlog, n * sz); - *unit_size = sz; + memcpy(buffer, detlog, n * sizeof(detlog[0])); + *unit_size = sizeof(detlog[0]); *num_stored = n; // Then shift back the remaining items memmove(detlog, detlog + n, (detlog_length - n) * sizeof(detlog[0])); detlog_length -= n; - mtx_unlock(&detlog_mutex); +unlock_return: + mtx_unlock(&state_mutex); } -void set_gchook() { - if (mtx_init(&detlog_mutex, mtx_plain) != thrd_success) { - fprintf(stderr, "ghc-gc-hook: ERROR: Mutex initialisation failed\n"); - return; +// Sets the GC hook, logging or C hook delegate not yet enabled. Returns success. +bool set_gchook(void) { + if (mtx_lock(&state_mutex) != thrd_success) { + fprintf(stderr, "ghc-gc-hook: ERROR: Mutex lock failed\n"); + return false; + } + + bool retval = false; + + if (!constructor_worked) { + fprintf(stderr, "ghc-gc-hook: ERROR: Cannot set hook, system does not allow initialisation\n"); + goto unlock_return_retval; + } + + if (hook_initialised) { + fprintf(stderr, "ghc-gc-hook: ERROR: Hook already initialised\n"); + goto unlock_return_retval; } old_hook = rtsConfig.gcDoneHook; rtsConfig.gcDoneHook = hook_callback; + + hook_initialised = true; + retval = true; + +unlock_return_retval: + mtx_unlock(&state_mutex); + return retval; +} + +// Enable logging on the GC hook. +void gchook_enable_logging(bool yes) { + if (!hook_initialised) { + if (!set_gchook()) exit(1); // meh + } + + if (mtx_lock(&state_mutex) != thrd_success) { + fprintf(stderr, "ghc-gc-hook: ERROR: Mutex lock failed\n"); + return; + } + + if (logging_enabled && !yes) { + detlog_length = 0; + detlog_capacity = 0; + free(detlog); + detlog = NULL; + } + + logging_enabled = yes; + + mtx_unlock(&state_mutex); +} + +// Set a C function to be called after every GC with the GCDetails_ structure +// from `rts/include/RtsAPI.h`. Returns success. +bool gchook_set_c_delegate(void (*delegate)(const struct GCDetails_*)) { + if (!hook_initialised) { + if (!set_gchook()) exit(1); // meh + } + + if (mtx_lock(&state_mutex) != thrd_success) { + fprintf(stderr, "ghc-gc-hook: ERROR: Mutex lock failed\n"); + return false; + } + + bool retval = false; + + if (hook_c_delegate != NULL) { + fprintf(stderr, "ghc-gc-hook: ERROR: C hook delegate already set\n"); + goto unlock_return_retval; + } + + hook_c_delegate = delegate; + retval = true; + +unlock_return_retval: + mtx_unlock(&state_mutex); + return retval; } |