1 files changed, 155 insertions, 0 deletions
diff --git a/common/state/backend_bucket_cached.c b/common/state/backend_bucket_cached.c
new file mode 100644
index 0000000000..781ac2debd
--- /dev/null
+++ b/common/state/backend_bucket_cached.c
@@ -0,0 +1,155 @@
+/*
+ * Copyright (C) 2016 Pengutronix, Markus Pargmann <mpa@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <common.h>
+#include "state.h"
+
+struct state_backend_storage_bucket_cache {
+	struct state_backend_storage_bucket bucket;
+
+	struct state_backend_storage_bucket *raw;
+
+	u8 *data;
+	ssize_t data_len;
+	bool force_write;
+
+	/* For outputs */
+	struct device_d *dev;
+};
+
+static inline struct state_backend_storage_bucket_cache
+    *get_bucket_cache(struct state_backend_storage_bucket *bucket)
+{
+	return container_of(bucket,
+			    struct state_backend_storage_bucket_cache,
+			    bucket);
+}
+
+static inline void state_backend_bucket_cache_drop(
+		struct state_backend_storage_bucket_cache *cache)
+{
+	if (cache->data) {
+		free(cache->data);
+		cache->data = NULL;
+		cache->data_len = 0;
+	}
+}
+
+static int state_backend_bucket_cache_fill(
+		struct state_backend_storage_bucket_cache *cache)
+{
+	int ret;
+
+	ret = cache->raw->read(cache->raw, &cache->data, &cache->data_len);
+	if (ret == -EUCLEAN)
+		cache->force_write = true;
+	else if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int state_backend_bucket_cache_read(struct state_backend_storage_bucket *bucket,
+					   uint8_t ** buf_out,
+					   ssize_t * len_hint)
+{
+	struct state_backend_storage_bucket_cache *cache =
+			get_bucket_cache(bucket);
+	int ret;
+
+	if (!cache->data) {
+		ret = state_backend_bucket_cache_fill(cache);
+		if (ret)
+			return ret;
+	}
+
+	if (cache->data) {
+		*buf_out = xmemdup(cache->data, cache->data_len);
+		if (!*buf_out)
+			return -ENOMEM;
+		*len_hint = cache->data_len;
+	}
+
+	return 0;
+}
+
+static int state_backend_bucket_cache_write(struct state_backend_storage_bucket *bucket,
+					    const uint8_t * buf, ssize_t len)
+{
+	struct state_backend_storage_bucket_cache *cache =
+			get_bucket_cache(bucket);
+	int ret;
+
+	if (!cache->force_write) {
+		if (!cache->data)
+			ret = state_backend_bucket_cache_fill(cache);
+
+		if (cache->data_len == len && !memcmp(cache->data, buf, len))
+			return 0;
+	}
+
+	state_backend_bucket_cache_drop(cache);
+
+	ret = cache->raw->write(cache->raw, buf, len);
+	if (ret)
+		return ret;
+
+	cache->data = xmemdup(buf, len);
+	cache->data_len = len;
+	return 0;
+}
+
+static int state_backend_bucket_cache_init(
+		struct state_backend_storage_bucket *bucket)
+{
+	struct state_backend_storage_bucket_cache *cache =
+			get_bucket_cache(bucket);
+
+	if (cache->raw->init) {
+		return cache->raw->init(cache->raw);
+	}
+
+	return 0;
+}
+
+static void state_backend_bucket_cache_free(
+		struct state_backend_storage_bucket *bucket)
+{
+	struct state_backend_storage_bucket_cache *cache =
+			get_bucket_cache(bucket);
+
+	state_backend_bucket_cache_drop(cache);
+	cache->raw->free(cache->raw);
+	free(cache);
+}
+
+int state_backend_bucket_cached_create(struct device_d *dev,
+				       struct state_backend_storage_bucket *raw,
+				       struct state_backend_storage_bucket **out)
+{
+	struct state_backend_storage_bucket_cache *cache;
+
+	cache = xzalloc(sizeof(*cache));
+	cache->raw = raw;
+	cache->dev = dev;
+
+	cache->bucket.free = state_backend_bucket_cache_free;
+	cache->bucket.read = state_backend_bucket_cache_read;
+	cache->bucket.write = state_backend_bucket_cache_write;
+	cache->bucket.init = state_backend_bucket_cache_init;
+
+	*out = &cache->bucket;
+
+	return 0;
+}