* Wrap deleteFromStore() in a transaction. Otherwise there might be a

  race with other processes that add new referrers to a path,
  resulting in the garbage collector crashing with "foreign key
  constraint failed".  (Nix/4)
* Make --gc --print-dead etc. interruptible.

1 files changed, 8 insertions, 5 deletions

diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index c0c1461b4974..c0c75e34d502 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -298,11 +298,10 @@ void LocalStore::openDB(bool create)
     if (sqlite3_exec(db, ("pragma synchronous = " + syncMode + ";").c_str(), 0, 0, 0) != SQLITE_OK)
         throw SQLiteError(db, "setting synchronous mode");
 
-    /* Set the SQLite journal mode.  The default is write-ahead
-       logging since it's the fastest and supports more concurrency.
-       The downside is that it doesn't work over NFS, so allow
-       truncate mode alternatively. */
-    string mode = queryBoolSetting("use-sqlite-wal", true) ? "wal" : "truncate";
+    /* Set the SQLite journal mode.  WAL mode is fastest, but doesn't
+       seem entirely stable at the moment (Oct. 2010).  Thus, use
+       truncate mode by default. */
+    string mode = queryBoolSetting("use-sqlite-wal", false) ? "wal" : "truncate";
     string prevMode;
     {
         SQLiteStmt stmt;
@@ -1220,6 +1219,8 @@ void LocalStore::deleteFromStore(const Path & path, unsigned long long & bytesFr
 
     assertStorePath(path);
 
+    SQLiteTxn txn(db);
+
     if (isValidPath(path)) {
         PathSet referrers; queryReferrers(path, referrers);
         referrers.erase(path); /* ignore self-references */
@@ -1230,6 +1231,8 @@ void LocalStore::deleteFromStore(const Path & path, unsigned long long & bytesFr
     }
 
     deletePathWrapped(path, bytesFreed, blocksFreed);
+
+    txn.commit();
 }