Introduce threading

In order to enable deferred events from grail, but the event
processing in a separate thread, and have the calling thread return
as quickly as possible.

Signed-off-by: Henrik Rydberg <rydberg@bitmath.org>

1 files changed, 71 insertions, 4 deletions

diff --git a/src/grail-api.c b/src/grail-api.c
index 19b66aa..e3b8125 100644
--- a/src/grail-api.c
+++ b/src/grail-api.c
@@ -1,6 +1,8 @@
 #include "grail-inserter.h"
 #include "grail-recognizer.h"
 #include <grail.h>
+#include <pthread.h>
+#include <signal.h>
 #include <string.h>
 #include <stdio.h>
 #include <unistd.h>
@@ -9,12 +11,48 @@
 #include <errno.h>
 #include "evbuf.h"
 
+static const pthread_mutex_t c_mutex =  PTHREAD_MUTEX_INITIALIZER;
+static const pthread_cond_t c_wait = PTHREAD_COND_INITIALIZER;
+
 struct grail_impl {
         struct touch_dev dev;
         struct touch_engine engine;
         struct evbuf evbuf;
+        int fd;
+        int pull, finished;
+        pthread_mutex_t mutex;
+        pthread_cond_t wait;
+        pthread_t thread;
 };
 
+/*
+ * While not finished, lock, wait for condition, extract the running
+ * state, unlock, then process the event queue.
+ *
+ * The processing may in principle take seconds to complete without
+ * locking up the writer side.
+ */
+static void *grail_thread(void *priv)
+{
+        struct grail_impl *x = priv;
+        int pull, finished = 0;
+        sigset_t block;
+        sigemptyset(&block);
+        sigaddset(&block, SIGIO);
+        pthread_sigmask(SIG_BLOCK, &block, NULL);
+        while (!finished) {
+                pthread_mutex_lock(&x->mutex);
+                pthread_cond_wait(&x->wait, &x->mutex);
+                pull = x->pull;
+                finished = x->finished;
+                x->pull = 0;
+                pthread_mutex_unlock(&x->mutex);
+                if (!finished && pull)
+                        touch_dev_process(&x->dev);
+        }
+        pthread_exit(NULL);
+}
+
 static void tp_event(struct touch_engine *engine,
                      const struct input_event *ev)
 {
@@ -66,10 +104,18 @@ int grail_open(struct grail *ge, int fd)
         ret = touch_dev_open(&x->dev, fd);
         if (ret)
                 goto freegru;
+        x->fd = fd;
+        x->mutex = c_mutex;
+        x->wait = c_wait;
+        ret = pthread_create(&x->thread, NULL, grail_thread, x);
+        if (ret)
+                goto freetouch;
+        ge->impl = x;
         touch_engine_init(&x->engine, tp_event, tp_sync, ge);
         touch_engine_attach(&x->engine, &x->dev);
-        ge->impl = x;
         return 0;
+ freetouch:
+        touch_dev_close(&x->dev, fd);
  freegru:
         gru_destroy(ge);
  freedev:
@@ -82,6 +128,11 @@ int grail_open(struct grail *ge, int fd)
 void grail_close(struct grail *ge, int fd)
 {
         struct grail_impl *x = ge->impl;
+        void *status;
+        pthread_mutex_lock(&x->mutex);
+        x->finished = 1;
+        pthread_cond_signal (&x->wait);
+        pthread_mutex_unlock(&x->mutex);
         touch_engine_detach(&x->engine, &x->dev);
         touch_dev_close(&x->dev, fd);
         gru_destroy(ge);
@@ -93,12 +144,28 @@ void grail_close(struct grail *ge, int fd)
 int grail_idle(struct grail *ge, int fd, int ms)
 {
         struct grail_impl *x = ge->impl;
-        return touch_dev_idle(&x->dev, fd, ms);
+        int ret;
+        pthread_mutex_lock(&x->mutex);
+        ret = touch_dev_idle(&x->dev, fd, ms);
+        pthread_mutex_unlock(&x->mutex);
+        return ret;
 }
 
+/*
+ * First extract all input events to a lockless circular buffer, then,
+ * under lock, signal the worker thread.
+ *
+ * This function only blocks temporarily while signalling the worker
+ * thread.
+ */
 int grail_pull(struct grail *ge, int fd)
 {
         struct grail_impl *x = ge->impl;
-        return touch_dev_pull(&x->dev, fd);
+        int finished = touch_dev_fetch(&x->dev, fd) < 0;
+        pthread_mutex_lock(&x->mutex);
+        x->pull = 1;
+        x->finished = finished;
+        pthread_cond_signal(&x->wait);
+        pthread_mutex_unlock(&x->mutex);
+        return 1;
 }
-