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, 23 insertions, 11 deletions

diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index cac137a99..9870e36b5 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -63,13 +63,16 @@ Path followLinksToStorePath(const Path & path)
 string storePathToName(const Path & path)
 {
     assertStorePath(path);
-    return string(path, settings.nixStore.size() + storePathHashLen + 2);
+    auto l = settings.nixStore.size() + 1 + storePathHashLen;
+    assert(path.size() >= l);
+    return path.size() == l ? "" : string(path, l + 1);
 }
 
 
 string storePathToHash(const Path & path)
 {
     assertStorePath(path);
+    assert(path.size() >= settings.nixStore.size() + 1 + storePathHashLen);
     return string(path, settings.nixStore.size() + 1, storePathHashLen);
 }
 
@@ -234,9 +237,11 @@ std::string Store::getUri()
 
 bool Store::isValidPath(const Path & storePath)
 {
+    auto hashPart = storePathToHash(storePath);
+
     {
         auto state_(state.lock());
-        auto res = state_->pathInfoCache.get(storePath);
+        auto res = state_->pathInfoCache.get(hashPart);
         if (res) {
             stats.narInfoReadAverted++;
             return *res != 0;
@@ -244,10 +249,11 @@ bool Store::isValidPath(const Path & storePath)
     }
 
     if (diskCache) {
-        auto res = diskCache->lookupNarInfo(getUri(), storePath);
+        auto res = diskCache->lookupNarInfo(getUri(), hashPart);
         if (res.first != NarInfoDiskCache::oUnknown) {
+            stats.narInfoReadAverted++;
             auto state_(state.lock());
-            state_->pathInfoCache.upsert(storePath,
+            state_->pathInfoCache.upsert(hashPart,
                 res.first == NarInfoDiskCache::oInvalid ? 0 : res.second);
             return res.first == NarInfoDiskCache::oValid;
         }
@@ -261,9 +267,11 @@ bool Store::isValidPath(const Path & storePath)
 
 ref<const ValidPathInfo> Store::queryPathInfo(const Path & storePath)
 {
+    auto hashPart = storePathToHash(storePath);
+
     {
         auto state_(state.lock());
-        auto res = state_->pathInfoCache.get(storePath);
+        auto res = state_->pathInfoCache.get(hashPart);
         if (res) {
             stats.narInfoReadAverted++;
             if (!*res)
@@ -273,12 +281,14 @@ ref<const ValidPathInfo> Store::queryPathInfo(const Path & storePath)
     }
 
     if (diskCache) {
-        auto res = diskCache->lookupNarInfo(getUri(), storePath);
+        auto res = diskCache->lookupNarInfo(getUri(), hashPart);
         if (res.first != NarInfoDiskCache::oUnknown) {
+            stats.narInfoReadAverted++;
             auto state_(state.lock());
-            state_->pathInfoCache.upsert(storePath,
+            state_->pathInfoCache.upsert(hashPart,
                 res.first == NarInfoDiskCache::oInvalid ? 0 : res.second);
-            if (res.first == NarInfoDiskCache::oInvalid)
+            if (res.first == NarInfoDiskCache::oInvalid ||
+                (res.second->path != storePath && storePathToName(storePath) != ""))
                 throw InvalidPath(format("path ‘%s’ is not valid") % storePath);
             return ref<ValidPathInfo>(res.second);
         }
@@ -287,14 +297,16 @@ ref<const ValidPathInfo> Store::queryPathInfo(const Path & storePath)
     auto info = queryPathInfoUncached(storePath);
 
     if (diskCache && info)
-        diskCache->upsertNarInfo(getUri(), info);
+        diskCache->upsertNarInfo(getUri(), hashPart, info);
 
     {
         auto state_(state.lock());
-        state_->pathInfoCache.upsert(storePath, info);
+        state_->pathInfoCache.upsert(hashPart, info);
     }
 
-    if (!info) {
+    if (!info
+        || (info->path != storePath && storePathToName(storePath) != ""))
+    {
         stats.narInfoMissing++;
         throw InvalidPath(format("path ‘%s’ is not valid") % storePath);
     }