Merge "Use sequence number to check if to reload atrace tags." (445234c7) · Commits · e / os / android_system_core

libcutils/include/cutils/trace.h

+21 −6

Original line number	Diff line number	Diff line
		@@ -25,7 +25,6 @@
		#include <sys/cdefs.h>
		#include <sys/types.h>
		#include <unistd.h>

		#include <cutils/compiler.h>

		__BEGIN_DECLS
		@@ -89,6 +88,12 @@ __BEGIN_DECLS
		#error ATRACE_TAG must be defined to be one of the tags defined in cutils/trace.h
		#endif

		// Set this to 0 to revert to the old Binder-based atrace implementation.
		// This is only here in case rollbacks do not apply cleanly.
		// TODO(fmayer): Remove this once we are confident this won't need to be
		// rolled back, no later than 2020-03-01.
		#define ATRACE_SHMEM 1

		/**
		* Opens the trace file for writing and reads the property for initial tags.
		* The atrace.tags.enableflags property sets the tags to trace.
		@@ -116,11 +121,15 @@ void atrace_set_debuggable(bool debuggable);
		* prevent tracing within the Zygote process.
		*/
		void atrace_set_tracing_enabled(bool enabled);

		/**
		* If !ATRACE_SHMEM:
		* Flag indicating whether setup has been completed, initialized to 0.
		* Nonzero indicates setup has completed.
		* Note: This does NOT indicate whether or not setup was successful.
		* If ATRACE_SHMEM:
		* This is always set to false. This forces code that uses an old version
		* of this header to always call into atrace_setup, in which we call
		* atrace_init unconditionally.
		*/
		extern atomic_bool atrace_is_ready;

		@@ -143,6 +152,12 @@ extern int atrace_marker_fd;
		* This can be explicitly run to avoid setup delay on first trace function.
		*/
		#define ATRACE_INIT() atrace_init()
		#define ATRACE_GET_ENABLED_TAGS() atrace_get_enabled_tags()

		#if ATRACE_SHMEM
		void atrace_init();
		uint64_t atrace_get_enabled_tags();
		#else
		static inline void atrace_init()
		{
		if (CC_UNLIKELY(!atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) {
		@@ -155,12 +170,12 @@ static inline void atrace_init()
		* It can be used as a guard condition around more expensive trace calculations.
		* Every trace function calls this, which ensures atrace_init is run.
		*/
		#define ATRACE_GET_ENABLED_TAGS() atrace_get_enabled_tags()
		static inline uint64_t atrace_get_enabled_tags()
		{
		atrace_init();
		return atrace_enabled_tags;
		}
		#endif

		/**
		* Test if a given tag is currently enabled.

libcutils/trace-container.cpp

+5 −0

Original line number	Diff line number	Diff line
		@@ -39,6 +39,11 @@ static int atrace_container_sock_fd = -1;
		static pthread_mutex_t atrace_enabling_mutex = PTHREAD_MUTEX_INITIALIZER;
		static pthread_rwlock_t atrace_container_sock_rwlock = PTHREAD_RWLOCK_INITIALIZER;

		static void atrace_seq_number_changed(uint32_t, uint32_t seq_no) {
		pthread_once(&atrace_once_control, atrace_init_once);
		atomic_store_explicit(&last_sequence_number, seq_no, memory_order_relaxed);
		}

		static bool atrace_init_container_sock()
		{
		pthread_rwlock_wrlock(&atrace_container_sock_rwlock);

libcutils/trace-dev.cpp

+27 −0

Original line number	Diff line number	Diff line
		@@ -37,12 +37,39 @@ static void atrace_init_once()
		} 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)

libcutils/trace-dev.inc

+57 −7

Original line number	Diff line number	Diff line
		@@ -34,6 +34,11 @@
		#include <log/log.h>
		#include <log/log_properties.h>

		#if defined(__BIONIC__)
		#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
		#include <sys/_system_properties.h>
		#endif

		/**
		* Maximum size of a message that can be logged to the trace buffer.
		* Note this message includes a tag, the pid, and the string given as the name.
		@@ -41,6 +46,8 @@
		*/
		#define ATRACE_MESSAGE_LENGTH 1024

		constexpr uint32_t kSeqNoNotInit = static_cast<uint32_t>(-1);

		atomic_bool atrace_is_ready = ATOMIC_VAR_INIT(false);
		int atrace_marker_fd = -1;
		uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY;
		@@ -48,6 +55,49 @@ static bool atrace_is_debuggable = false;
		static atomic_bool atrace_is_enabled = ATOMIC_VAR_INIT(true);
		static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER;

		/**
		* Sequence number of debug.atrace.tags.enableflags the last time the enabled
		* tags were reloaded.
		**/
		static _Atomic(uint32_t) last_sequence_number = ATOMIC_VAR_INIT(kSeqNoNotInit);

		#if defined(__BIONIC__)
		// All zero prop_info that has a sequence number of 0. This is easier than
		// depending on implementation details of the property implementation.
		//
		// prop_info is static_assert-ed to be 96 bytes, which cannot change due to
		// ABI compatibility.
		alignas(uint64_t) static char empty_pi[96];
		static const prop_info* atrace_property_info = reinterpret_cast<const prop_info*>(empty_pi);
		#endif

		#if ATRACE_SHMEM

		/**
		* This is called when the sequence number of debug.atrace.tags.enableflags
		* changes and we need to reload the enabled tags.
		**/
		static void atrace_seq_number_changed(uint32_t prev_seq_no, uint32_t seq_no);

		void atrace_init() {
		#if defined(__BIONIC__)
		uint32_t seq_no = __system_property_serial(atrace_property_info); // Acquire semantics.
		#else
		uint32_t seq_no = 0;
		#endif
		uint32_t prev_seq_no = atomic_load_explicit(&last_sequence_number, memory_order_relaxed);
		if (CC_UNLIKELY(seq_no != prev_seq_no)) {
		atrace_seq_number_changed(prev_seq_no, seq_no);
		}
		}

		uint64_t atrace_get_enabled_tags()
		{
		atrace_init();
		return atrace_enabled_tags;
		}
		#endif

		// Set whether this process is debuggable, which determines whether
		// application-level tracing is allowed when the ro.debuggable system property
		// is not set to '1'.
		@@ -136,7 +186,7 @@ static uint64_t atrace_get_property()
		void atrace_update_tags()
		{
		uint64_t tags;
		if (CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) {
		if (ATRACE_SHMEM \|\| CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) {
		if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) {
		tags = atrace_get_property();
		pthread_mutex_lock(&atrace_tags_mutex);

libcutils/trace-host.cpp

+7 −0

Original line number	Diff line number	Diff line
		@@ -30,3 +30,10 @@ void atrace_async_begin_body(const char* /name/, int32_t /cookie/) {}
		void atrace_async_end_body(const char* /name/, int32_t /cookie/) {}
		void atrace_int_body(const char* /name/, int32_t /value/) {}
		void atrace_int64_body(const char* /name/, int64_t /value/) {}
		#if ATRACE_SHMEM
		void atrace_init() {}
		uint64_t atrace_get_enabled_tags()
		{
		return ATRACE_TAG_NOT_READY;
		}
		#endif