Merge pull request #4781 from NixOS/locally_cache_the_remote_realisations

Add a realisations disk cache

1 files changed, 98 insertions, 1 deletions

diff --git a/src/libstore/nar-info-disk-cache.cc b/src/libstore/nar-info-disk-cache.cc
index 1d8d2d57e..9dd81ddfb 100644
--- a/src/libstore/nar-info-disk-cache.cc
+++ b/src/libstore/nar-info-disk-cache.cc
@@ -4,6 +4,7 @@
 #include "globals.hh"
 
 #include <sqlite3.h>
+#include <nlohmann/json.hpp>
 
 namespace nix {
 
@@ -38,6 +39,15 @@ create table if not exists NARs (
     foreign key (cache) references BinaryCaches(id) on delete cascade
 );
 
+create table if not exists Realisations (
+    cache integer not null,
+    outputId text not null,
+    content blob, -- Json serialisation of the realisation, or null if the realisation is absent
+    timestamp        integer not null,
+    primary key (cache, outputId),
+    foreign key (cache) references BinaryCaches(id) on delete cascade
+);
+
 create table if not exists LastPurge (
     dummy            text primary key,
     value            integer
@@ -63,7 +73,9 @@ public:
     struct State
     {
         SQLite db;
-        SQLiteStmt insertCache, queryCache, insertNAR, insertMissingNAR, queryNAR, purgeCache;
+        SQLiteStmt insertCache, queryCache, insertNAR, insertMissingNAR,
+            queryNAR, insertRealisation, insertMissingRealisation,
+            queryRealisation, purgeCache;
         std::map<std::string, Cache> caches;
     };
 
@@ -98,6 +110,26 @@ public:
         state->queryNAR.create(state->db,
             "select present, namePart, url, compression, fileHash, fileSize, narHash, narSize, refs, deriver, sigs, ca from NARs where cache = ? and hashPart = ? and ((present = 0 and timestamp > ?) or (present = 1 and timestamp > ?))");
 
+        state->insertRealisation.create(state->db,
+            R"(
+                insert or replace into Realisations(cache, outputId, content, timestamp)
+                    values (?, ?, ?, ?)
+            )");
+
+        state->insertMissingRealisation.create(state->db,
+            R"(
+                insert or replace into Realisations(cache, outputId, timestamp)
+                    values (?, ?, ?)
+            )");
+
+        state->queryRealisation.create(state->db,
+            R"(
+                select content from Realisations
+                    where cache = ? and outputId = ?  and
+                        ((content is null and timestamp > ?) or
+                         (content is not null and timestamp > ?))
+            )");
+
         /* Periodically purge expired entries from the database. */
         retrySQLite<void>([&]() {
             auto now = time(0);
@@ -212,6 +244,38 @@ public:
         });
     }
 
+    std::pair<Outcome, std::shared_ptr<Realisation>> lookupRealisation(
+        const std::string & uri, const DrvOutput & id) override
+    {
+        return retrySQLite<std::pair<Outcome, std::shared_ptr<Realisation>>>(
+            [&]() -> std::pair<Outcome, std::shared_ptr<Realisation>> {
+            auto state(_state.lock());
+
+            auto & cache(getCache(*state, uri));
+
+            auto now = time(0);
+
+            auto queryRealisation(state->queryRealisation.use()
+                (cache.id)
+                (id.to_string())
+                (now - settings.ttlNegativeNarInfoCache)
+                (now - settings.ttlPositiveNarInfoCache));
+
+            if (!queryRealisation.next())
+                return {oUnknown, 0};
+
+            if (queryRealisation.isNull(0))
+                return {oInvalid, 0};
+
+            auto realisation =
+                std::make_shared<Realisation>(Realisation::fromJSON(
+                    nlohmann::json::parse(queryRealisation.getStr(0)),
+                    "Local disk cache"));
+
+            return {oValid, realisation};
+        });
+    }
+
     void upsertNarInfo(
         const std::string & uri, const std::string & hashPart,
         std::shared_ptr<const ValidPathInfo> info) override
@@ -251,6 +315,39 @@ public:
             }
         });
     }
+
+    void upsertRealisation(
+        const std::string & uri,
+        const Realisation & realisation) override
+    {
+        retrySQLite<void>([&]() {
+            auto state(_state.lock());
+
+            auto & cache(getCache(*state, uri));
+
+            state->insertRealisation.use()
+                (cache.id)
+                (realisation.id.to_string())
+                (realisation.toJSON().dump())
+                (time(0)).exec();
+        });
+
+    }
+
+    virtual void upsertAbsentRealisation(
+        const std::string & uri,
+        const DrvOutput & id) override
+    {
+        retrySQLite<void>([&]() {
+            auto state(_state.lock());
+
+            auto & cache(getCache(*state, uri));
+            state->insertMissingRealisation.use()
+                (cache.id)
+                (id.to_string())
+                (time(0)).exec();
+        });
+    }
 };
 
 ref<NarInfoDiskCache> getNarInfoDiskCache()