cutils: Add tracing support
Basic tracing functionality to cutils, which can be turned on at start,
or dynamically controlled by the frameworks. The goal is for hardware
modules to add tracing that will be controlled by their respective
services.
Change-Id: I84eeb7d6be0038f734e719074fa4a2fae4ffe9c0
diff --git a/libcutils/trace.c b/libcutils/trace.c
new file mode 100644
index 0000000..15c8a98
--- /dev/null
+++ b/libcutils/trace.c
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <cutils/atomic.h>
+#include <cutils/compiler.h>
+#include <cutils/properties.h>
+#include <cutils/trace.h>
+
+#define LOG_TAG "cutils-trace"
+#include <cutils/log.h>
+
+int32_t atrace_is_ready = 0;
+int atrace_marker_fd = -1;
+uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY;
+static pthread_once_t atrace_once_control = PTHREAD_ONCE_INIT;
+
+// Read the sysprop and return the value tags should be set to
+static uint64_t atrace_get_property()
+{
+ char value[PROPERTY_VALUE_MAX];
+ char *endptr;
+ uint64_t tags;
+
+ property_get("debug.atrace.tags.enableflags", value, "0");
+ errno = 0;
+ tags = strtoull(value, &endptr, 0);
+ if (value[0] == '\0' || *endptr != '\0') {
+ ALOGE("Error parsing trace property: Not a number: %s", value);
+ return 0;
+ } else if (errno == ERANGE || tags == ULLONG_MAX) {
+ ALOGE("Error parsing trace property: Number too large: %s", value);
+ return 0;
+ }
+ return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK;
+}
+
+static void atrace_init_once()
+{
+ atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY);
+ if (atrace_marker_fd == -1) {
+ ALOGE("Error opening trace file: %s (%d)", strerror(errno), errno);
+ atrace_enabled_tags = 0;
+ goto done;
+ }
+
+ atrace_enabled_tags = atrace_get_property();
+
+done:
+ android_atomic_release_store(1, &atrace_is_ready);
+}
+
+void atrace_setup()
+{
+ pthread_once(&atrace_once_control, atrace_init_once);
+}