On windows, allow many entries in conscache directories

Since we can't be sure that we can unlink enough files on windows
here, let's let the number of permitted entries grow huge if it
really must.

We do this by letting the storagedir hold lots of entries, but still
trying to keep the number of entries under the configured limit.  We
also have to tell consdiffmgr not to freak out if it can't actually
remove enough entries.

Part of a fix for bug 22752

diff --git a/src/or/conscache.c b/src/or/conscache.c
index c30d1998c61c6881b8f4a0487b3d37de590e2192..350a05b0f222d7924acc610d0d1a5ad08bb8a3ab 100644 (file)
--- a/src/or/conscache.c
+++ b/src/or/conscache.c
@@ -54,6 +54,11 @@ struct consensus_cache_t {
   storage_dir_t *dir;
   /** List of all the entries in the directory. */
   smartlist_t *entries;
+
+  /** The maximum number of entries that we'd like to allow in this cache.
+   * This is the same as the storagedir limit when MUST_UNMAP_TO_UNLINK is
+   * not defined. */
+  unsigned max_entries;
 };
 
 static void consensus_cache_clear(consensus_cache_t *cache);
@@ -71,6 +76,10 @@ consensus_cache_open(const char *subdir, int max_entries)
 {
   consensus_cache_t *cache = tor_malloc_zero(sizeof(consensus_cache_t));
   char *directory = get_datadir_fname(subdir);
+  cache->max_entries = max_entries;
+#ifdef MUST_UNMAP_TO_UNLINK
+  max_entries = 1000000;
+#endif
   cache->dir = storage_dir_new(directory, max_entries);
   tor_free(directory);
   if (!cache->dir) {
@@ -82,6 +91,19 @@ consensus_cache_open(const char *subdir, int max_entries)
   return cache;
 }
 
+/** Return true if it's okay to put more entries in this cache than
+ * its official file limit. */
+int
+consensus_cache_may_overallocate(consensus_cache_t *cache)
+{
+  (void) cache;
+#ifdef MUST_UNMAP_TO_UNLINK
+  return 1;
+#else
+  return 0;
+#endif
+}
+
 /**
  * Tell the sandbox (if any) configured by <b>cfg</b> to allow the
  * operations that <b>cache</b> will need.
@@ -90,6 +112,11 @@ int
 consensus_cache_register_with_sandbox(consensus_cache_t *cache,
                                       struct sandbox_cfg_elem **cfg)
 {
+#ifdef MUST_UNMAP_TO_UNLINK
+  /* Our sandbox doesn't support huge limits like we use here.
+   */
+  tor_assert_nonfatal_unreached();
+#endif
   return storage_dir_register_with_sandbox(cache->dir, cfg);
 }
 

diff --git a/src/or/conscache.h b/src/or/conscache.h
index aef54201f0be93109b0f3bb8a9ec52170531ef8e..a0d74c4e0805f856347db0beb141761074bb594d 100644 (file)
--- a/src/or/conscache.h
+++ b/src/or/conscache.h
@@ -14,6 +14,7 @@ HANDLE_DECL(consensus_cache_entry, consensus_cache_entry_t, )
 consensus_cache_t *consensus_cache_open(const char *subdir, int max_entries);
 void consensus_cache_free(consensus_cache_t *cache);
 struct sandbox_cfg_elem;
+int consensus_cache_may_overallocate(consensus_cache_t *cache);
 int consensus_cache_register_with_sandbox(consensus_cache_t *cache,
                                           struct sandbox_cfg_elem **cfg);
 void consensus_cache_unmap_lazy(consensus_cache_t *cache, time_t cutoff);

diff --git a/src/or/consdiffmgr.c b/src/or/consdiffmgr.c
index 928fc26f545898cf8f1b3e022a2e7091a30d31ed..831d5d45c387e364cb6776093ea9b291f45e10b2 100644 (file)
--- a/src/or/consdiffmgr.c
+++ b/src/or/consdiffmgr.c
@@ -1136,7 +1136,7 @@ consdiffmgr_ensure_space_for_files(int n)
     return 0;
   }
   // Let's get more assertive: clean out unused stuff, and force-remove
-  // the files.
+  // the files that we can.
   consdiffmgr_cleanup();
   consensus_cache_delete_pending(cache, 1);
   const int n_to_remove = n - consensus_cache_get_n_filenames_available(cache);
@@ -1159,6 +1159,14 @@ consdiffmgr_ensure_space_for_files(int n)
   smartlist_free(objects);
 
   consensus_cache_delete_pending(cache, 1);
+
+  if (consensus_cache_may_overallocate(cache)) {
+    /* If we're allowed to throw extra files into the cache, let's do so
+     * rather getting upset.
+     */
+    return 0;
+  }
+
   if (BUG(n_marked < n_to_remove))
     return -1;
   else