Factor out a LogStore interface

src/libstore/binary-cache-store.hh

@@ -2,6 +2,7 @@
 
 #include "crypto.hh"
 #include "store-api.hh"
+#include "log-store.hh"
 
 #include "pool.hh"
 
@@ -28,7 +29,9 @@ struct BinaryCacheStoreConfig : virtual StoreConfig
         "other than -1 which we reserve to indicate Nix defaults should be used"};
 };
 
-class BinaryCacheStore : public virtual BinaryCacheStoreConfig, public virtual Store
+class BinaryCacheStore : public virtual BinaryCacheStoreConfig,
+    public virtual Store,
+    public virtual LogStore
 {
 
 private:

src/libstore/build/local-derivation-goal.cc

@@ -1340,6 +1340,12 @@ struct RestrictedStore : public virtual RestrictedStoreConfig, public virtual Lo
         next->queryMissing(allowed, willBuild, willSubstitute,
             unknown, downloadSize, narSize);
     }
+
+    virtual std::optional<std::string> getBuildLog(const StorePath & path) override
+    { return std::nullopt; }
+
+    virtual void addBuildLog(const StorePath & path, std::string_view log) override
+    { unsupported("addBuildLog"); }
 };
 
 

src/libstore/daemon.cc

@@ -3,7 +3,9 @@
 #include "worker-protocol.hh"
 #include "build-result.hh"
 #include "store-api.hh"
+#include "store-cast.hh"
 #include "gc-store.hh"
+#include "log-store.hh"
 #include "path-with-outputs.hh"
 #include "finally.hh"
 #include "archive.hh"
@@ -645,7 +647,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         Path path = absPath(readString(from));
 
         logger->startWork();
-        auto & gcStore = requireGcStore(*store);
+        auto & gcStore = require<GcStore>(*store);
         gcStore.addIndirectRoot(path);
         logger->stopWork();
 
@@ -663,7 +665,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
 
     case wopFindRoots: {
         logger->startWork();
-        auto & gcStore = requireGcStore(*store);
+        auto & gcStore = require<GcStore>(*store);
         Roots roots = gcStore.findRoots(!trusted);
         logger->stopWork();
 
@@ -695,7 +697,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         logger->startWork();
         if (options.ignoreLiveness)
             throw Error("you are not allowed to ignore liveness");
-        auto & gcStore = requireGcStore(*store);
+        auto & gcStore = require<GcStore>(*store);
         gcStore.collectGarbage(options, results);
         logger->stopWork();
 
@@ -953,11 +955,12 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         logger->startWork();
         if (!trusted)
             throw Error("you are not privileged to add logs");
+        auto & logStore = require<LogStore>(*store);
         {
             FramedSource source(from);
             StringSink sink;
             source.drainInto(sink);
-            store->addBuildLog(path, sink.s);
+            logStore.addBuildLog(path, sink.s);
         }
         logger->stopWork();
         to << 1;

src/libstore/gc-store.hh

@@ -61,6 +61,8 @@ struct GCResults
 
 struct GcStore : public virtual Store
 {
+    inline static std::string operationName = "Garbage collection";
+
     /* Add an indirect root, which is merely a symlink to `path' from
        /nix/var/nix/gcroots/auto/<hash of `path'>.  `path' is supposed
        to be a symlink to a store path.  The garbage collector will
@@ -79,6 +81,4 @@ struct GcStore : public virtual Store
     virtual void collectGarbage(const GCOptions & options, GCResults & results) = 0;
 };
 
-GcStore & requireGcStore(Store & store);
-
 }

src/libstore/local-fs-store.hh

@@ -2,6 +2,7 @@
 
 #include "store-api.hh"
 #include "gc-store.hh"
+#include "log-store.hh"
 
 namespace nix {
 
@@ -24,7 +25,10 @@ struct LocalFSStoreConfig : virtual StoreConfig
         "physical path to the Nix store"};
 };
 
-class LocalFSStore : public virtual LocalFSStoreConfig, public virtual Store, virtual GcStore
+class LocalFSStore : public virtual LocalFSStoreConfig,
+    public virtual Store,
+    public virtual GcStore,
+    public virtual LogStore
 {
 public:
 

src/libstore/log-store.hh

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "store-api.hh"
+
+
+namespace nix {
+
+struct LogStore : public virtual Store
+{
+    inline static std::string operationName = "Build log storage and retrieval";
+
+    /* Return the build log of the specified store path, if available,
+       or null otherwise. */
+    virtual std::optional<std::string> getBuildLog(const StorePath & path) = 0;
+
+    virtual void addBuildLog(const StorePath & path, std::string_view log) = 0;
+
+    static LogStore & require(Store & store);
+};
+
+}

src/libstore/remote-store.hh

@@ -5,6 +5,7 @@
 
 #include "store-api.hh"
 #include "gc-store.hh"
+#include "log-store.hh"
 
 
 namespace nix {
@@ -30,7 +31,10 @@ struct RemoteStoreConfig : virtual StoreConfig
 
 /* FIXME: RemoteStore is a misnomer - should be something like
    DaemonStore. */
-class RemoteStore : public virtual RemoteStoreConfig, public virtual Store, public virtual GcStore
+class RemoteStore : public virtual RemoteStoreConfig,
+    public virtual Store,
+    public virtual GcStore,
+    public virtual LogStore
 {
 public:
 

src/libstore/ssh-store.cc

@@ -52,6 +52,10 @@ class SSHStore : public virtual SSHStoreConfig, public virtual RemoteStore
     bool sameMachine() override
     { return false; }
 
+    // FIXME extend daemon protocol, move implementation to RemoteStore
+    std::optional<std::string> getBuildLog(const StorePath & path) override
+    { unsupported("getBuildLog"); }
+
 private:
 
     struct Connection : RemoteStore::Connection

src/libstore/store-api.hh

@@ -605,14 +605,6 @@ public:
      */
     StorePathSet exportReferences(const StorePathSet & storePaths, const StorePathSet & inputPaths);
 
-    /* Return the build log of the specified store path, if available,
-       or null otherwise. */
-    virtual std::optional<std::string> getBuildLog(const StorePath & path)
-    { return std::nullopt; }
-
-    virtual void addBuildLog(const StorePath & path, std::string_view log)
-    { unsupported("addBuildLog"); }
-
     /* Hack to allow long-running processes like hydra-queue-runner to
        occasionally flush their path info cache. */
     void clearPathInfoCache()

src/libstore/store-cast.hh

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "store-api.hh"
+
+namespace nix {
+
+template<typename T>
+T & require(Store & store)
+{
+    auto * castedStore = dynamic_cast<T *>(&store);
+    if (!castedStore)
+        throw UsageError("%s not supported by store '%s'", T::operationName, store.getUri());
+    return *castedStore;
+}
+
+}

src/nix-collect-garbage/nix-collect-garbage.cc

@@ -1,4 +1,5 @@
 #include "store-api.hh"
+#include "store-cast.hh"
 #include "gc-store.hh"
 #include "profiles.hh"
 #include "shared.hh"
@@ -81,7 +82,7 @@ static int main_nix_collect_garbage(int argc, char * * argv)
         // Run the actual garbage collector.
         if (!dryRun) {
             auto store = openStore();
-            auto & gcStore = requireGcStore(*store);
+            auto & gcStore = require<GcStore>(*store);
             options.action = GCOptions::gcDeleteDead;
             GCResults results;
             PrintFreed freed(true, results);

src/nix-store/nix-store.cc

@@ -3,7 +3,9 @@
 #include "dotgraph.hh"
 #include "globals.hh"
 #include "build-result.hh"
+#include "store-cast.hh"
 #include "gc-store.hh"
+#include "log-store.hh"
 #include "local-store.hh"
 #include "monitor-fd.hh"
 #include "serve-protocol.hh"
@@ -429,7 +431,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
             store->computeFSClosure(
                 args, referrers, true, settings.gcKeepOutputs, settings.gcKeepDerivations);
 
-            auto & gcStore = requireGcStore(*store);
+            auto & gcStore = require<GcStore>(*store);
             Roots roots = gcStore.findRoots(false);
             for (auto & [target, links] : roots)
                 if (referrers.find(target) != referrers.end())
@@ -474,13 +476,15 @@ static void opReadLog(Strings opFlags, Strings opArgs)
 {
     if (!opFlags.empty()) throw UsageError("unknown flag");
 
+    auto & logStore = require<LogStore>(*store);
+
     RunPager pager;
 
     for (auto & i : opArgs) {
-        auto path = store->followLinksToStorePath(i);
-        auto log = store->getBuildLog(path);
+        auto path = logStore.followLinksToStorePath(i);
+        auto log = logStore.getBuildLog(path);
         if (!log)
-            throw Error("build log of derivation '%s' is not available", store->printStorePath(path));
+            throw Error("build log of derivation '%s' is not available", logStore.printStorePath(path));
         std::cout << *log;
     }
 }
@@ -590,7 +594,7 @@ static void opGC(Strings opFlags, Strings opArgs)
 
     if (!opArgs.empty()) throw UsageError("no arguments expected");
 
-    auto & gcStore = requireGcStore(*store);
+    auto & gcStore = require<GcStore>(*store);
 
     if (printRoots) {
         Roots roots = gcStore.findRoots(false);
@@ -629,7 +633,7 @@ static void opDelete(Strings opFlags, Strings opArgs)
     for (auto & i : opArgs)
         options.pathsToDelete.insert(store->followLinksToStorePath(i));
 
-    auto & gcStore = requireGcStore(*store);
+    auto & gcStore = require<GcStore>(*store);
 
     GCResults results;
     PrintFreed freed(true, results);

src/nix/log.cc

@@ -2,6 +2,7 @@
 #include "common-args.hh"
 #include "shared.hh"
 #include "store-api.hh"
+#include "log-store.hh"
 #include "progress-bar.hh"
 
 using namespace nix;
@@ -34,17 +35,24 @@ struct CmdLog : InstallableCommand
 
         RunPager pager;
         for (auto & sub : subs) {
+            auto * logSubP = dynamic_cast<LogStore *>(&*sub);
+            if (!logSubP) {
+                printInfo("Skipped '%s' which does not support retrieving build logs", sub->getUri());
+                continue;
+            }
+            auto & logSub = *logSubP;
+
             auto log = std::visit(overloaded {
                 [&](const DerivedPath::Opaque & bo) {
-                    return sub->getBuildLog(bo.path);
+                    return logSub.getBuildLog(bo.path);
                 },
                 [&](const DerivedPath::Built & bfd) {
-                    return sub->getBuildLog(bfd.drvPath);
+                    return logSub.getBuildLog(bfd.drvPath);
                 },
             }, b.raw());
             if (!log) continue;
             stopProgressBar();
-            printInfo("got build log for '%s' from '%s'", installable->what(), sub->getUri());
+            printInfo("got build log for '%s' from '%s'", installable->what(), logSub.getUri());
             std::cout << *log;
             return;
         }

src/nix/repl.cc

@@ -25,6 +25,7 @@ extern "C" {
 #include "eval-inline.hh"
 #include "attr-path.hh"
 #include "store-api.hh"
+#include "log-store.hh"
 #include "common-eval-args.hh"
 #include "get-drvs.hh"
 #include "derivations.hh"
@@ -526,9 +527,16 @@ bool NixRepl::processLine(std::string line)
             bool foundLog = false;
             RunPager pager;
             for (auto & sub : subs) {
-                auto log = sub->getBuildLog(drvPath);
+                auto * logSubP = dynamic_cast<LogStore *>(&*sub);
+                if (!logSubP) {
+                    printInfo("Skipped '%s' which does not support retrieving build logs", sub->getUri());
+                    continue;
+                }
+                auto & logSub = *logSubP;
+
+                auto log = logSub.getBuildLog(drvPath);
                 if (log) {
-                    printInfo("got build log for '%s' from '%s'", drvPathRaw, sub->getUri());
+                    printInfo("got build log for '%s' from '%s'", drvPathRaw, logSub.getUri());
                     logger->writeToStdout(*log);
                     foundLog = true;
                     break;

src/nix/store-copy-log.cc

@@ -1,6 +1,8 @@
 #include "command.hh"
 #include "shared.hh"
 #include "store-api.hh"
+#include "store-cast.hh"
+#include "log-store.hh"
 #include "sync.hh"
 #include "thread-pool.hh"
 
@@ -26,7 +28,10 @@ struct CmdCopyLog : virtual CopyCommand, virtual InstallablesCommand
 
     void run(ref<Store> srcStore) override
     {
+        auto & srcLogStore = require<LogStore>(*srcStore);
+
         auto dstStore = getDstStore();
+        auto & dstLogStore = require<LogStore>(*dstStore);
 
         StorePathSet drvPaths;
 
@@ -35,8 +40,8 @@ struct CmdCopyLog : virtual CopyCommand, virtual InstallablesCommand
                 drvPaths.insert(drvPath);
 
         for (auto & drvPath : drvPaths) {
-            if (auto log = srcStore->getBuildLog(drvPath))
-                dstStore->addBuildLog(drvPath, *log);
+            if (auto log = srcLogStore.getBuildLog(drvPath))
+                dstLogStore.addBuildLog(drvPath, *log);
             else
                 throw Error("build log for '%s' is not available", srcStore->printStorePath(drvPath));
         }

src/nix/store-delete.cc

@@ -2,6 +2,7 @@
 #include "common-args.hh"
 #include "shared.hh"
 #include "store-api.hh"
+#include "store-cast.hh"
 #include "gc-store.hh"
 
 using namespace nix;
@@ -33,7 +34,7 @@ struct CmdStoreDelete : StorePathsCommand
 
     void run(ref<Store> store, std::vector<StorePath> && storePaths) override
     {
-        auto & gcStore = requireGcStore(*store);
+        auto & gcStore = require<GcStore>(*store);
 
         for (auto & path : storePaths)
             options.pathsToDelete.insert(path);