[PATCH] Add an 'optimiseStore' RPC

[Ludovic Courtès]

Hi Eelco,

The patch below adds an ‘optimiseStore’ RPC, and thus adds a mandatory
‘optimiseStore’ method in ‘StoreAPI’.

OK to commit?

Ludo’.

diff --git a/src/libstore/local-store.hh b/src/libstore/local-store.hh
index 09639e7..4404ffc 100644
--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -168,6 +168,9 @@ public:
        files with the same contents. */
     void optimiseStore(OptimiseStats & stats);
 
+    /* Generic variant of the above method.  */
+    void optimiseStore();
+
     /* Optimise a single store path. */
     void optimisePath(const Path & path);
 
diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index d833f3a..68acb6e 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -169,6 +169,24 @@ void LocalStore::optimiseStore(OptimiseStats & stats)
     }
 }
 
+static string showBytes(unsigned long long bytes)
+{
+    return (format("%.2f MiB") % (bytes / (1024.0 * 1024.0))).str();
+}
+
+void LocalStore::optimiseStore()
+{
+    OptimiseStats stats;
+
+    optimiseStore(stats);
+
+    printMsg(lvlError,
+        format("%1% freed by hard-linking %2% files; there are %3% files with 
equal contents out of %4% files in total")
+        % showBytes(stats.bytesFreed)
+        % stats.filesLinked
+        % stats.sameContents
+        % stats.totalFiles);
+}
 
 void LocalStore::optimisePath(const Path & path)
 {
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 4619206..8e1bfdb 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -564,6 +564,13 @@ void RemoteStore::clearFailedPaths(const PathSet & paths)
     readInt(from);
 }
 
+void RemoteStore::optimiseStore()
+{
+    openConnection();
+    writeInt(wopOptimiseStore, to);
+    processStderr();
+    readInt(from);
+}
 
 void RemoteStore::processStderr(Sink * sink, Source * source)
 {
diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 04b60fc..b9b7f7c 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -82,7 +82,9 @@ public:
     PathSet queryFailedPaths();
 
     void clearFailedPaths(const PathSet & paths);
-    
+
+    void optimiseStore();
+
 private:
     AutoCloseFD fdSocket;
     FdSink to;
diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
index b635fee..3109f10 100644
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -250,6 +250,10 @@ public:
        `nix-store --register-validity'. */
     string makeValidityRegistration(const PathSet & paths,
         bool showDerivers, bool showHash);
+
+    /* Optimise the disk space usage of the Nix store by hard-linking files
+       with the same contents. */
+    virtual void optimiseStore() = 0;
 };
 
 
diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh
index 9317f89..9a3d83a 100644
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@@ -43,6 +43,7 @@ typedef enum {
     wopQueryValidPaths = 31,
     wopQuerySubstitutablePaths = 32,
     wopQueryValidDerivers = 33,
+    wopOptimiseStore = 34
 } WorkerOp;
 
 
diff --git a/src/nix-daemon/nix-daemon.cc b/src/nix-daemon/nix-daemon.cc
index 8814fe3..413db20 100644
--- a/src/nix-daemon/nix-daemon.cc
+++ b/src/nix-daemon/nix-daemon.cc
@@ -650,6 +650,13 @@ static void performOp(bool trusted, unsigned int 
clientVersion,
         break;
     }
 
+    case wopOptimiseStore:
+       startWork();
+       store->optimiseStore();
+       stopWork();
+       writeInt(1, to);
+       break;
+
     default:
         throw Error(format("invalid operation %1%") % op);
     }
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 341a4f6..e13bfe9 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -798,17 +798,6 @@ static void opRepairPath(Strings opFlags, Strings opArgs)
 }
 
 
-static void showOptimiseStats(OptimiseStats & stats)
-{
-    printMsg(lvlError,
-        format("%1% freed by hard-linking %2% files; there are %3% files with 
equal contents out of %4% files in total")
-        % showBytes(stats.bytesFreed)
-        % stats.filesLinked
-        % stats.sameContents
-        % stats.totalFiles);
-}
-
-
 /* Optimise the disk space usage of the Nix store by hard-linking
    files with the same contents. */
 static void opOptimise(Strings opFlags, Strings opArgs)
@@ -816,17 +805,9 @@ static void opOptimise(Strings opFlags, Strings opArgs)
     if (!opArgs.empty() || !opFlags.empty())
         throw UsageError("no arguments expected");
 
-    OptimiseStats stats;
-    try {
-        ensureLocalStore().optimiseStore(stats);
-    } catch (...) {
-        showOptimiseStats(stats);
-        throw;
-    }
-    showOptimiseStats(stats);
+    store->optimiseStore();
 }
 
-
 static void opQueryFailedPaths(Strings opFlags, Strings opArgs)
 {
     if (!opArgs.empty() || !opFlags.empty())