Implement S3BinaryCacheStore::queryAllValidPaths()

This allows commands like "nix verify --all" or "nix path-info --all"
to work on S3 caches.

Unfortunately, this requires some ugly hackery: when querying the
contents of the bucket, we don't want to have to read every .narinfo
file. But the S3 bucket keys only include the hash part of each store
path, not the name part. So as a special exception
queryAllValidPaths() can now return store paths *without* the name
part, and queryPathInfo() accepts such store paths (returning a
ValidPathInfo object containing the full name).

1 files changed, 8 insertions, 3 deletions

diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index eab6da91e..e0cc32296 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -181,7 +181,7 @@ protected:
 
     struct State
     {
-        LRUCache<Path, std::shared_ptr<ValidPathInfo>> pathInfoCache{64 * 1024};
+        LRUCache<std::string, std::shared_ptr<ValidPathInfo>> pathInfoCache{64 * 1024};
     };
 
     Sync<State> state;
@@ -206,10 +206,15 @@ public:
     /* Query which of the given paths is valid. */
     virtual PathSet queryValidPaths(const PathSet & paths) = 0;
 
-    /* Query the set of all valid paths. */
+    /* Query the set of all valid paths. Note that for some store
+       backends, the name part of store paths may be omitted
+       (i.e. you'll get /nix/store/<hash> rather than
+       /nix/store/<hash>-<name>). Use queryPathInfo() to obtain the
+       full store path. */
     virtual PathSet queryAllValidPaths() = 0;
 
-    /* Query information about a valid path. */
+    /* Query information about a valid path. It is permitted to omit
+       the name part of the store path. */
     ref<const ValidPathInfo> queryPathInfo(const Path & path);
 
 protected: