nix-store: implement --query --uncached

Resolves NixOS#3946 by providing an efficient means of querying cache status of the passed paths. For every path passed, it will be returned on standard output only if it is not available in any of the configured substituters.
nrdxp · Dec 29, 2022 · 5e3e6fe · 5e3e6fe
1 parent 3dbf9b5
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diff --git a/doc/manual/src/command-ref/nix-store.md b/doc/manual/src/command-ref/nix-store.md
@@ -281,7 +281,7 @@ error: cannot delete path `/nix/store/zq0h41l75vlb4z45kzgjjmsjxvcv1qk7-mesa-6.4'
   {`--outputs` | `--requisites` | `-R` | `--references` |
   `--referrers` | `--referrers-closure` | `--deriver` | `-d` |
   `--graph` | `--tree` | `--binding` *name* | `-b` *name* | `--hash` |
-  `--size` | `--roots`}
+  `--size` | `--roots` | `--uncached` | `-U`}
   [`--use-output`] [`-u`] [`--force-realise`] [`-f`]
   *paths…*
 
@@ -397,6 +397,10 @@ symlink.
     Prints the garbage collector roots that point, directly or
     indirectly, at the store paths *paths*.
 
+  - `--uncached`; `-U`\
+    Outputs a list of the store paths *paths* which are not available in
+    any configured caches.
+
 ## Examples
 
 Print the closure (runtime dependencies) of the `svn` program in the
@@ -435,6 +439,16 @@ $ nix-store -q --tree $(nix-store -qd $(which svn))
 ...
 ```
 
+Show uncached build & runtime dependencies:
+
+```console
+$ drv=$(nix-store -qd $(which svn))
+$ nix-store -qU $(nix-store -qR --include-outputs $drv)
+/nix/store/5mbglq5ldqld8sj57273aljwkfvj22mc-subversion-1.1.4
+/nix/store/9lz9yc6zgmc0vlqmn2ipcpkjlmbi51vv-glibc-2.3.4
+...
+```
+
 Show all paths that depend on the same OpenSSL library as `svn`:
 
 ```console

diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
@@ -15,6 +15,8 @@
 #include "graphml.hh"
 #include "legacy.hh"
 #include "path-with-outputs.hh"
+#include "filetransfer.hh"
+#include "thread-pool.hh"
 
 #include <iostream>
 #include <algorithm>
@@ -24,6 +26,8 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 
+#include <nlohmann/json.hpp>
+
 
 namespace nix_store {
 
@@ -276,7 +280,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
     enum QueryType
         { qDefault, qOutputs, qRequisites, qReferences, qReferrers
         , qReferrersClosure, qDeriver, qBinding, qHash, qSize
-        , qTree, qGraph, qGraphML, qResolve, qRoots };
+        , qTree, qGraph, qGraphML, qResolve, qRoots, qUncached };
     QueryType query = qDefault;
     bool useOutput = false;
     bool includeOutputs = false;
@@ -300,6 +304,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
         }
         else if (i == "--hash") query = qHash;
         else if (i == "--size") query = qSize;
+        else if (i == "--uncached" || i == "-U") query = qUncached;
         else if (i == "--tree") query = qTree;
         else if (i == "--graph") query = qGraph;
         else if (i == "--graphml") query = qGraphML;
@@ -364,6 +369,32 @@ static void opQuery(Strings opFlags, Strings opArgs)
             }
             break;
 
+        case qUncached: {
+            if (opArgs.empty()) throw UsageError("no paths passed");
+
+            ThreadPool pool(fileTransferSettings.httpConnections);
+
+            std::function<void(StorePath)> queryPath;
+            queryPath = [&](const StorePath & req) {
+                SubstitutablePathInfos infos;
+                store->querySubstitutablePathInfos({{req, std::nullopt}}, infos);
+
+                if (infos.empty()) {
+                    cout << store->printStorePath(req) << '\n';
+                }
+            };
+
+            for (auto & i : opArgs) {
+                auto path = store->followLinksToStorePath(i);
+
+                pool.enqueue(std::bind(queryPath, path));
+            }
+
+            pool.process();
+
+            break;
+        }
+
         case qBinding:
             for (auto & i : opArgs) {
                 auto path = useDeriver(store->followLinksToStorePath(i));
@@ -680,7 +711,6 @@ static void opExport(Strings opFlags, Strings opArgs)
     sink.flush();
 }
 
-
 static void opImport(Strings opFlags, Strings opArgs)
 {
     for (auto & i : opFlags)