[datapipe] Allow data caching at output stage. JB#37393

Reading cached value from a datapipe gives the last input fed to the
datapipe. If the datapipe uses input filters, the cached input value
can differ from the latest output value that was reported via output
triggers.

Make it possible to update datapipe cache in the output stage too via
using caching policy CACHE_OUTDATA.

Signed-off-by: Simo Piiroinen <simo.piiroinen@jollamobile.com>

datapipe.c

@@ -232,8 +232,7 @@ datapipe_struct proximity_blank_pipe;
  */
 void execute_datapipe_input_triggers(datapipe_struct *const datapipe,
 				     gpointer const indata,
-				     const data_source_t use_cache,
-				     const caching_policy_t cache_indata)
+				     const data_source_t use_cache)
 {
 	void (*trigger)(gconstpointer const input);
 	gpointer data;
@@ -249,15 +248,6 @@ void execute_datapipe_input_triggers(datapipe_struct *const datapipe,
 
 	data = (use_cache == USE_CACHE) ? datapipe->cached_data : indata;
 
-	if (cache_indata == CACHE_INDATA) {
-		if (use_cache == USE_INDATA) {
-			if (datapipe->free_cache == FREE_CACHE)
-				g_free(datapipe->cached_data);
-
-			datapipe->cached_data = data;
-		}
-	}
-
 	for (i = 0; (trigger = g_slist_nth_data(datapipe->input_triggers,
 						i)) != NULL; i++) {
 		trigger(data);
@@ -298,12 +288,14 @@ gconstpointer execute_datapipe_filters(datapipe_struct *const datapipe,
 					       i)) != NULL; i++) {
 		gpointer tmp = filter(data);
 
-		/* If the data needs to be freed, and this isn't the indata,
-		 * or if we're not using the cache, then free the data
-		 */
-		if ((datapipe->free_cache == FREE_CACHE) &&
-		    ((i > 0) || (use_cache == USE_INDATA)))
-			g_free(data);
+		if( datapipe->free_cache == FREE_CACHE ) {
+			/* When dealing with dynamic data, the transitional
+			 * values need to be released - except for the value
+			 * that is cached at the datapipe
+			 */
+			if( tmp != data && data != datapipe->cached_data )
+				g_free(data);
+		}
 
 		data = tmp;
 	}
@@ -364,7 +356,7 @@ gconstpointer execute_datapipe(datapipe_struct *const datapipe,
 			       const data_source_t use_cache,
 			       const caching_policy_t cache_indata)
 {
-	gconstpointer data = NULL;
+	gconstpointer outdata = NULL;
 
 	if (datapipe == NULL) {
 		mce_log(LL_ERR,
@@ -373,19 +365,42 @@ gconstpointer execute_datapipe(datapipe_struct *const datapipe,
 		goto EXIT;
 	}
 
-	execute_datapipe_input_triggers(datapipe, indata, use_cache,
-					cache_indata);
+	/* Determine input value */
+	if( use_cache == USE_CACHE )
+		indata = datapipe->cached_data;
 
+	/* Optionally cache the value at the input stage */
+	if( cache_indata & (CACHE_INDATA|CACHE_OUTDATA) ) {
+		if( datapipe->free_cache == FREE_CACHE &&
+		    datapipe->cached_data != indata )
+			g_free(datapipe->cached_data);
+		datapipe->cached_data = indata;
+	}
+
+	/* Execute input value callbacks */
+	execute_datapipe_input_triggers(datapipe, indata, USE_INDATA);
+
+	/* Determine output value */
 	if (datapipe->read_only == READ_ONLY) {
-		data = indata;
+		outdata = indata;
 	} else {
-		data = execute_datapipe_filters(datapipe, indata, use_cache);
+		outdata = execute_datapipe_filters(datapipe, indata, USE_INDATA);
+	}
+
+	/* Optionally cache the value at the output stage */
+	if( cache_indata & CACHE_OUTDATA ) {
+		if( datapipe->free_cache == FREE_CACHE &&
+		    datapipe->cached_data != outdata )
+			g_free(datapipe->cached_data);
+
+		datapipe->cached_data = (gpointer)outdata;
 	}
 
-	execute_datapipe_output_triggers(datapipe, data, USE_INDATA);
+	/* Execute output value callbacks */
+	execute_datapipe_output_triggers(datapipe, outdata, USE_INDATA);
 
 EXIT:
-	return data;
+	return outdata;
 }
 
 /**

datapipe.h

@@ -82,8 +82,9 @@ typedef enum {
  * Policy used for caching indata
  */
 typedef enum {
-	DONT_CACHE_INDATA = FALSE,	/**< Do not cache the indata */
-	CACHE_INDATA = TRUE		/**< Cache the indata */
+	DONT_CACHE_INDATA = 0,          /**< Do not cache the indata */
+	CACHE_INDATA      = 1<<0,       /**< Cache the unfiltered indata */
+	CACHE_OUTDATA     = 1<<1,       /**< Cache the filtered outdata */
 } caching_policy_t;
 
 /* Available datapipes */
@@ -170,8 +171,7 @@ extern datapipe_struct proximity_blank_pipe;
 /* Datapipe execution */
 void execute_datapipe_input_triggers(datapipe_struct *const datapipe,
 				     gpointer const indata,
-				     const data_source_t use_cache,
-				     const caching_policy_t cache_indata);
+				     const data_source_t use_cache);
 gconstpointer execute_datapipe_filters(datapipe_struct *const datapipe,
 				       gpointer indata,
 				       const data_source_t use_cache);