Introduce a cache quota: BDRVCURLState.cache_quota. When adding new CURLDataCache to BDRVCURLState, if number of existing CURLDataCache is larger than CURL_CACHE_QUOTA, try to release some first to limit the in memory cache size.
A least used entry is selected for releasing. Signed-off-by: Fam Zheng <f...@redhat.com> --- block/curl.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/block/curl.c b/block/curl.c index f7358de..f4e2571 100644 --- a/block/curl.c +++ b/block/curl.c @@ -40,6 +40,7 @@ #define SECTOR_SIZE 512 #define READ_AHEAD_SIZE (256 * 1024) +#define CURL_CACHE_QUOTA 10 struct BDRVCURLState; @@ -90,6 +91,8 @@ typedef struct BDRVCURLState { QEMUTimer *timer; /* List of data cache ordered by access, freed from tail */ QLIST_HEAD(, CURLDataCache) cache; + /* Threshold to release unused cache when cache list is longer than it */ + int cache_quota; /* Whether http server accept range in header */ bool accept_range; } BDRVCURLState; @@ -518,6 +521,8 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags) curl_multi_socket_action(s->multi, CURL_SOCKET_TIMEOUT, 0, &running); qemu_opts_del(opts); + s->cache_quota = CURL_CACHE_QUOTA; + return 0; out: @@ -587,6 +592,27 @@ static void curl_readv_bh_cb(void *p) cache->data_len = aio_bytes + s->readahead_size; cache->write_pos = 0; cache->data = g_malloc(cache->data_len); + /* Try to release some cache */ + while (0 && s->cache_quota <= 0) { + CURLDataCache *p; + CURLDataCache *q = NULL; + assert(!QLIST_EMPTY(&s->cache)); + for (p = QLIST_FIRST(&s->cache); + p; p = QLIST_NEXT(p, next)) { + if (p->use_count == 0) { + q = p; + } + } + if (!q) { + break; + } + QLIST_REMOVE(q, next); + g_free(q->data); + q->data = NULL; + g_free(q); + q = NULL; + s->cache_quota++; + } QLIST_INSERT_HEAD(&s->acbs, acb, next); snprintf(state->range, sizeof(state->range) - 1, "%zd-%zd", cache->base_pos, @@ -597,6 +623,7 @@ static void curl_readv_bh_cb(void *p) QLIST_INSERT_HEAD(&s->cache, cache, next); state->cache = cache; cache->use_count++; + s->cache_quota--; curl_multi_add_handle(s->multi, state->curl); /* kick off curl to start the action */ curl_multi_socket_action(s->multi, 0, CURL_SOCKET_TIMEOUT, &running); -- 1.8.1.4