1 files changed, 137 insertions, 0 deletions
diff --git a/cmds/runtime/SignalHandler.h b/cmds/runtime/SignalHandler.h
new file mode 100644
index 0000000..7f4ef8e
--- /dev/null
+++ b/cmds/runtime/SignalHandler.h
@@ -0,0 +1,137 @@
+//
+// Copyright 2005 The Android Open Source Project
+//
+#ifndef ANDROID_SIGNAL_HANDLER_H
+#define ANDROID_SIGNAL_HANDLER_H
+
+#include <utils/KeyedVector.h>
+#include <utils/threads.h>
+
+#include <signal.h>
+
+namespace android {
+
+// ----------------------------------------------------------------------
+
+enum {
+    DEFAULT_PROCESS_TAG = 1
+};
+
+class SignalHandler
+{
+public:
+    typedef void (*child_callback_t)(pid_t child, void* userData);
+
+    /**
+     * Set a handler for when a child process exits.  By calling
+     * this, a waitpid() will be done when the child exits to remove
+     * it from the zombie state.  You can also optionally specify a
+     * handler to be called when the child exits.
+     * 
+     * If there is already a handler for this child process, it is
+     * replaced by this new handler.  In this case the old handler's
+     * function is not called.
+     * 
+     * @param childPid Process ID of child to watch.
+     * @param childTag User-defined tag for this child.  Must be
+     *                 greater than zero.
+     * @param handler If non-NULL, this will be called when the
+     *                child exits.  It may be called in either a
+     *                separate signal handling thread, or
+     *                immediately if the child has already exited.
+     * @param userData Propageted as-is to handler.
+     * 
+     * @return status_t NO_ERROR if all is well.
+     */
+    static status_t             setChildHandler(pid_t childPid,
+                                                int childTag = DEFAULT_PROCESS_TAG,
+                                                child_callback_t handler = NULL,
+                                                void* userData = NULL);
+
+    /**
+     * Kill all of the child processes for which we have a waiting
+     * handler, whose tag is the given value.  If tag is 0, all
+     * children are killed.
+     * 
+     * @param tag
+     */
+    static void                 killAllChildren(int tag = 0);
+
+private:
+                                SignalHandler();
+                                ~SignalHandler();
+
+    static SignalHandler*       getInstance();
+
+    static void                 sigAction(int, siginfo_t*, void*);
+
+    // --------------------------------------------------
+    // Shared state...  all of this is protected by mLock.
+    // --------------------------------------------------
+
+    mutable Mutex                       mLock;
+
+    struct ChildHandler
+    {
+        pid_t childPid;
+        int tag;
+        child_callback_t handler;
+        void* userData;
+    };
+    KeyedVector<pid_t, ChildHandler>    mChildHandlers;
+
+    // --------------------------------------------------
+    // Commmand queue...  data is inserted by the signal
+    // handler using atomic ops, and retrieved by the
+    // signal processing thread.  Because these are touched
+    // by the signal handler, no lock is used.
+    // --------------------------------------------------
+
+    enum {
+        COMMAND_QUEUE_SIZE = 64
+    };
+    struct CommandEntry
+    {
+        int filled;
+        int signum;
+        siginfo_t info;
+    };
+
+    // The top of the queue.  This is incremented atomically by the
+    // signal handler before placing a command in the queue.
+    volatile int32_t                    mCommandTop;
+
+    // The bottom of the queue.  Only modified by the processing
+    // thread; the signal handler reads it only to determine if the
+    // queue is full.
+    int32_t                             mCommandBottom;
+
+    // Incremented each time we receive a signal and don't have room
+    // for it on the command queue.
+    volatile int32_t                    mLostCommands;
+
+    // The command processing thread.
+    class ProcessThread;
+    sp<Thread>                          mProcessThread;
+
+    // Pipe used to tell command processing thread when new commands.
+    // are available.  The thread blocks on the read end, the signal
+    // handler writes when it enqueues new commands.
+    int                                 mAvailMsg[2];
+
+    // The commands.
+    CommandEntry                        mCommands[COMMAND_QUEUE_SIZE];
+
+    // --------------------------------------------------
+    // Singleton.
+    // --------------------------------------------------
+
+    static Mutex                        mInstanceLock;
+    static SignalHandler*               mInstance;
+};
+
+// ----------------------------------------------------------------------
+
+}; // namespace android
+
+#endif // ANDROID_SIGNAL_HANDLER_H