* First remote operation: isValidPath().

src/libstore/Makefile.am

@@ -6,7 +6,8 @@ libstore_la_SOURCES = \
 
 pkginclude_HEADERS = \
  store-api.hh local-store.cc remote-store.cc derivations.hh misc.hh \
- globals.hh db.hh references.hh pathlocks.hh gc.hh 
+ globals.hh db.hh references.hh pathlocks.hh gc.hh  \
+ worker-protocol.hh
 
 libstore_la_LIBADD = ../libutil/libutil.la ../boost/format/libformat.la
 

src/libstore/remote-store.cc

@@ -1,6 +1,7 @@
 #include "serialise.hh"
 #include "util.hh"
 #include "remote-store.hh"
+#include "worker-protocol.hh"
 
 #include <iostream>
 #include <unistd.h>
@@ -55,27 +56,36 @@ RemoteStore::RemoteStore()
 
     
     /* Send the magic greeting, check for the reply. */
-    writeInt(0x6e697864, to);
+    writeInt(WORKER_MAGIC_1, to);
     
     unsigned int magic = readInt(from);
-    if (magic != 0x6478696e) throw Error("protocol mismatch");
+    if (magic != WORKER_MAGIC_2) throw Error("protocol mismatch");
 }
 
 
 RemoteStore::~RemoteStore()
 {
+    writeInt(wopQuit, to);
+    readInt(from);
+    child.wait(true);
 }
 
 
 bool RemoteStore::isValidPath(const Path & path)
 {
-    throw Error("not implemented");
+    writeInt(wopIsValidPath, to);
+    writeString(path, to);
+    unsigned int reply = readInt(from);
+    return reply != 0;
 }
 
 
 Substitutes RemoteStore::querySubstitutes(const Path & srcPath)
 {
-    throw Error("not implemented");
+    //    writeInt(wopQuerySubstitutes);
+    
+    // throw Error("not implemented 2");
+    return Substitutes();
 }
 
 

src/libstore/worker-protocol.hh

@@ -0,0 +1,16 @@
+#ifndef __WORKER_PROTOCOL_H
+#define __WORKER_PROTOCOL_H
+
+
+#define WORKER_MAGIC_1 0x6e697864
+#define WORKER_MAGIC_2 0x6478696e
+
+
+typedef enum {
+    wopQuit = 0,
+    wopIsValidPath = 1,
+    wopQuerySubstitutes = 2,
+} WorkerOp;
+
+
+#endif /* !__WORKER_PROTOCOL_H */

src/nix-worker/main.cc

@@ -2,6 +2,7 @@
 #include "local-store.hh"
 #include "util.hh"
 #include "serialise.hh"
+#include "worker-protocol.hh"
 
 using namespace nix;
 
@@ -11,11 +12,39 @@ void processConnection(Source & from, Sink & to)
     store = boost::shared_ptr<StoreAPI>(new LocalStore(true));
 
     unsigned int magic = readInt(from);
-    if (magic != 0x6e697864) throw Error("protocol mismatch");
+    if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
 
-    writeInt(0x6478696e, to);
+    writeInt(WORKER_MAGIC_2, to);
 
     debug("greeting exchanged");
+
+    bool quit = false;
+    
+    do {
+        
+        WorkerOp op = (WorkerOp) readInt(from);
+
+        switch (op) {
+
+        case wopQuit:
+            /* Close the database. */
+            store.reset((StoreAPI *) 0);
+            writeInt(1, to);
+            quit = true;
+            break;
+
+        case wopIsValidPath: {
+            Path path = readString(from);
+            assertStorePath(path);
+            writeInt(store->isValidPath(path), to);
+            break;
+        }
+
+        default:
+            throw Error("invalid operation");
+        }
+        
+    } while (!quit);
 }