acquire_abort with no tears (#34)

* Remove additional camera_stop in acquire_abort().

* Revert "Remove additional camera_stop in acquire_abort()."

This reverts commit 1986628.

* Check camera is running on get_frame().

* Execute trigger abort, in case the camera is waiting on one.

* Update changelog.

* Update doc for `Camera.execute_trigger()`.

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - A bug where changing device identifiers for the storage device was not being handled correctly.
+- A race condition where `camera_get_frame()` might be called after `camera_stop()` when aborting acquisition.
 
 ### Changed
 

acquire-core-libs/src/acquire-device-hal/device/hal/camera.c

@@ -191,6 +191,7 @@ camera_get_frame(struct Camera* self,
                  struct ImageInfo* info)
 {
     CHECK(self);
+    CHECK(self->state == DeviceState_Running);
     enum DeviceStatusCode ecode = self->get_frame(self, im, nbytes, info);
     if (ecode != Device_Ok) {
         camera_stop(self);

acquire-core-libs/src/acquire-device-kit/device/kit/camera.h

@@ -47,7 +47,7 @@ extern "C"
         ///          (i.e. one call of start after one call of stop should succeed).
         enum DeviceStatusCode (*stop)(struct Camera*);
 
-        /// @brief Execute the software trigger if it's enabled.
+        /// @brief Execute the software trigger.
         enum DeviceStatusCode (*execute_trigger)(struct Camera*);
 
         /// @brief Gets the next frame from the camera.

acquire-video-runtime/src/acquire.c

@@ -575,7 +575,8 @@ acquire_abort(struct AcquireRuntime* self_)
 
         video->source.is_stopping = 1;
         channel_accept_writes(&video->sink.in, 0);
-        camera_stop(video->source.camera);
+        // if the camera is waiting on a trigger, this will unblock it.
+        camera_execute_trigger(video->source.camera);
     }
 
     return acquire_stop(self_);