utils: Add ProcessCallStack to collect stack traces for all threads in a process

- Also add a Printer class (print lines to logcat, fd, or strings)

Bug: 11324229
Change-Id: I78435ed49aa196a0efb45bf9b2d58b62c41737d3
diff --git a/include/utils/ProcessCallStack.h b/include/utils/ProcessCallStack.h
new file mode 100644
index 0000000..4a86869
--- /dev/null
+++ b/include/utils/ProcessCallStack.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#ifndef ANDROID_PROCESS_CALLSTACK_H
+#define ANDROID_PROCESS_CALLSTACK_H
+
+#include <utils/CallStack.h>
+#include <android/log.h>
+#include <utils/KeyedVector.h>
+#include <utils/String8.h>
+
+#include <time.h>
+#include <sys/types.h>
+
+namespace android {
+
+class Printer;
+
+// Collect/print the call stack (function, file, line) traces for all threads in a process.
+class ProcessCallStack {
+public:
+    // Create an empty call stack. No-op.
+    ProcessCallStack();
+    // Copy the existing process callstack (no other side effects).
+    ProcessCallStack(const ProcessCallStack& rhs);
+    ~ProcessCallStack();
+
+    // Immediately collect the stack traces for all threads.
+    void update(int32_t maxDepth = CallStack::MAX_DEPTH);
+
+    // Print all stack traces to the log using the supplied logtag.
+    void log(const char* logtag, android_LogPriority priority = ANDROID_LOG_DEBUG,
+             const char* prefix = 0) const;
+
+    // Dump all stack traces to the specified file descriptor.
+    void dump(int fd, int indent = 0, const char* prefix = 0) const;
+
+    // Return a string (possibly very long) containing all the stack traces.
+    String8 toString(const char* prefix = 0) const;
+
+    // Dump a serialized representation of all the stack traces to the specified printer.
+    void print(Printer& printer) const;
+
+    // Get the number of threads whose stack traces were collected.
+    size_t size() const;
+
+private:
+    void printInternal(Printer& printer, Printer& csPrinter) const;
+
+    // Reset the process's stack frames and metadata.
+    void clear();
+
+    struct ThreadInfo {
+        CallStack callStack;
+        String8 threadName;
+    };
+
+    // tid -> ThreadInfo
+    KeyedVector<pid_t, ThreadInfo> mThreadMap;
+    // Time that update() was last called
+    struct tm mTimeUpdated;
+};
+
+}; // namespace android
+
+#endif // ANDROID_PROCESS_CALLSTACK_H