From ccc52adfb2121ade510d35dc9b91193af9fa731e Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Tue, 17 Jul 2012 18:55:39 -0400 Subject: Add function queryPathFromHashPart() To implement binary caches efficiently, Hydra needs to be able to map the hash part of a store path (e.g. "gbg...zr7") to the full store path (e.g. "/nix/store/gbg...kzr7-subversion-1.7.5"). (The binary cache mechanism uses hash parts as a key for looking up store paths to ensure privacy.) However, doing a search in the Nix store for /nix/store/* is expensive since it requires reading the entire directory. queryPathFromHashPart() prevents this by doing a cheap database lookup. --- src/libstore/local-store.cc | 24 ++++++++++++++++++++++++ src/libstore/local-store.hh | 3 +++ src/libstore/remote-store.cc | 12 ++++++++++++ src/libstore/remote-store.hh | 2 ++ src/libstore/store-api.hh | 4 ++++ src/libstore/worker-protocol.hh | 1 + src/nix-worker/nix-worker.cc | 9 +++++++++ 7 files changed, 55 insertions(+) (limited to 'src') diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc index 1ce62aeafc..30398a2446 100644 --- a/src/libstore/local-store.cc +++ b/src/libstore/local-store.cc @@ -405,6 +405,10 @@ void LocalStore::openDB(bool create) "select v.id, v.path from DerivationOutputs d join ValidPaths v on d.drv = v.id where d.path = ?;"); stmtQueryDerivationOutputs.create(db, "select id, path from DerivationOutputs where drv = ?;"); + // Use "path >= ?" with limit 1 rather than "path like '?%'" to + // ensure efficient lookup. + stmtQueryPathFromHashPart.create(db, + "select path from ValidPaths where path >= ? limit 1;"); } @@ -865,6 +869,26 @@ StringSet LocalStore::queryDerivationOutputNames(const Path & path) } +Path LocalStore::queryPathFromHashPart(const string & hashPart) +{ + if (hashPart.size() != 32) throw Error("invalid hash part"); + + SQLiteTxn txn(db); + + Path prefix = nixStore + "/" + hashPart; + + SQLiteStmtUse use(stmtQueryPathFromHashPart); + stmtQueryPathFromHashPart.bind(prefix); + + int res = sqlite3_step(stmtQueryPathFromHashPart); + if (res == SQLITE_DONE) return ""; + if (res != SQLITE_ROW) throwSQLiteError(db, "finding path in database"); + + const char * s = (const char *) sqlite3_column_text(stmtQueryPathFromHashPart, 0); + return s && prefix.compare(0, prefix.size(), s, prefix.size()) == 0 ? s : ""; +} + + void LocalStore::startSubstituter(const Path & substituter, RunningSubstituter & run) { if (run.pid != -1) return; diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh index aa8e8582fb..65ee029c26 100644 --- a/src/libstore/local-store.hh +++ b/src/libstore/local-store.hh @@ -121,6 +121,8 @@ public: StringSet queryDerivationOutputNames(const Path & path); + Path queryPathFromHashPart(const string & hashPart); + PathSet querySubstitutablePaths(); bool hasSubstitutes(const Path & path); @@ -217,6 +219,7 @@ private: SQLiteStmt stmtAddDerivationOutput; SQLiteStmt stmtQueryValidDerivers; SQLiteStmt stmtQueryDerivationOutputs; + SQLiteStmt stmtQueryPathFromHashPart; int getSchema(); diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc index 5e5561a6ae..cbb70b2fd7 100644 --- a/src/libstore/remote-store.cc +++ b/src/libstore/remote-store.cc @@ -341,6 +341,18 @@ PathSet RemoteStore::queryDerivationOutputNames(const Path & path) } +Path RemoteStore::queryPathFromHashPart(const string & hashPart) +{ + openConnection(); + writeInt(wopQueryPathFromHashPart, to); + writeString(hashPart, to); + processStderr(); + Path path = readString(from); + if (!path.empty()) assertStorePath(path); + return path; +} + + Path RemoteStore::addToStore(const Path & _srcPath, bool recursive, HashType hashAlgo, PathFilter & filter) { diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh index e9f40da6db..f0e5dbf769 100644 --- a/src/libstore/remote-store.hh +++ b/src/libstore/remote-store.hh @@ -43,6 +43,8 @@ public: StringSet queryDerivationOutputNames(const Path & path); + Path queryPathFromHashPart(const string & hashPart); + bool hasSubstitutes(const Path & path); bool querySubstitutablePathInfo(const Path & path, diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh index bf3269f578..0ab15c3806 100644 --- a/src/libstore/store-api.hh +++ b/src/libstore/store-api.hh @@ -139,6 +139,10 @@ public: /* Query the output names of the derivation denoted by `path'. */ virtual StringSet queryDerivationOutputNames(const Path & path) = 0; + + /* Query the full store path given the hash part of a valid store + path, or "" if the path doesn't exist. */ + virtual Path queryPathFromHashPart(const string & hashPart) = 0; /* Query whether a path has substitutes. */ virtual bool hasSubstitutes(const Path & path) = 0; diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh index 6a5f0ed40d..b08410fa1c 100644 --- a/src/libstore/worker-protocol.hh +++ b/src/libstore/worker-protocol.hh @@ -40,6 +40,7 @@ typedef enum { wopQueryPathInfo = 26, wopImportPaths = 27, wopQueryDerivationOutputNames = 28, + wopQueryPathFromHashPart = 29, } WorkerOp; diff --git a/src/nix-worker/nix-worker.cc b/src/nix-worker/nix-worker.cc index 2f0a2ab209..74a619c71d 100644 --- a/src/nix-worker/nix-worker.cc +++ b/src/nix-worker/nix-worker.cc @@ -350,6 +350,15 @@ static void performOp(unsigned int clientVersion, break; } + case wopQueryPathFromHashPart: { + string hashPart = readString(from); + startWork(); + Path path = store->queryPathFromHashPart(hashPart); + stopWork(); + writeString(path, to); + break; + } + case wopAddToStore: { string baseName = readString(from); bool fixed = readInt(from) == 1; /* obsolete */ -- cgit 1.4.1