Use sequence number to check if to reload atrace tags.
This is to deprecate the sysprop change notification in atrace.
After this change, processes will only update their enabled tags
at the first atrace event. Previously we reloaded the tags as a
result of the sysprop changed Binder notification, which woke up
every process in the system.
Test: adb shell su root atrace -t 10 ss
Test: #define ATRACE_SHMEM 0; adb shell su root atrace -t 10 ss
Bug: 137366208
Change-Id: Idffba5fd4ba23fba2f6b9f594365df68ac0c1626
diff --git a/libcutils/trace-dev.cpp b/libcutils/trace-dev.cpp
index bff16c1..2ee39d3 100644
--- a/libcutils/trace-dev.cpp
+++ b/libcutils/trace-dev.cpp
@@ -37,12 +37,39 @@
} else {
atrace_enabled_tags = atrace_get_property();
}
+#if !ATRACE_SHMEM
atomic_store_explicit(&atrace_is_ready, true, memory_order_release);
+#endif
+}
+
+static void atrace_seq_number_changed(uint32_t prev_seq_no, uint32_t seq_no) {
+ if (!atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) {
+ return;
+ }
+
+ // Someone raced us.
+ if (!atomic_compare_exchange_strong(&last_sequence_number, &prev_seq_no, seq_no)) {
+ return;
+ }
+
+ if (CC_UNLIKELY(prev_seq_no == kSeqNoNotInit)) {
+#if defined(__BIONIC__)
+ const prop_info* new_pi = __system_property_find("debug.atrace.tags.enableflags");
+ if (new_pi) atrace_property_info = new_pi;
+#endif
+ pthread_once(&atrace_once_control, atrace_init_once);
+ }
+
+ atrace_update_tags();
}
void atrace_setup()
{
+#if ATRACE_SHMEM
+ atrace_init();
+#else
pthread_once(&atrace_once_control, atrace_init_once);
+#endif
}
void atrace_begin_body(const char* name)