Very basic multi-threaded queue runner

src/hydra-queue-runner/build-result.cc

@@ -6,7 +6,7 @@
 using namespace nix;
 
 
-BuildResult getBuildResult(const Derivation & drv)
+BuildResult getBuildResult(std::shared_ptr<StoreAPI> store, const Derivation & drv)
 {
     BuildResult res;
 

src/hydra-queue-runner/build-result.hh

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <memory>
+
 #include "hash.hh"
 #include "derivations.hh"
 
@@ -22,4 +24,4 @@ struct BuildResult
     std::list<BuildProduct> products;
 };
 
-BuildResult getBuildResult(const nix::Derivation & drv);
+BuildResult getBuildResult(std::shared_ptr<nix::StoreAPI> store, const nix::Derivation & drv);

src/hydra-queue-runner/hydra-queue-runner.cc

@@ -1,6 +1,10 @@
+#include <atomic>
+#include <condition_variable>
 #include <iostream>
-#include <memory>
 #include <map>
+#include <memory>
+#include <thread>
+
 #include <pqxx/pqxx>
 
 #include "build-result.hh"
@@ -12,6 +16,40 @@
 using namespace nix;
 
 
+std::mutex exitRequestMutex;
+std::condition_variable exitRequest;
+bool exitRequested(false);
+
+static std::atomic_int _int(0);
+
+void sigintHandler(int signo)
+{
+    _int = 1;
+}
+
+
+void signalThread()
+{
+    struct sigaction act;
+    act.sa_handler = sigintHandler;
+    sigemptyset(&act.sa_mask);
+    act.sa_flags = 0;
+    if (sigaction(SIGINT, &act, 0))
+        throw SysError("installing handler for SIGINT");
+
+    while (true) {
+        sleep(1000000);
+        if (_int) break;
+    }
+
+    {
+        std::lock_guard<std::mutex> lock(exitRequestMutex);
+        exitRequested = true;
+    }
+    exitRequest.notify_all();
+}
+
+
 typedef enum {
     bsSuccess = 0,
     bsFailed = 1,
@@ -74,6 +112,9 @@ struct Step
 class State
 {
 private:
+
+    std::thread queueMonitorThread;
+
     /* The queued builds. */
     std::map<BuildID, Build::ptr> builds;
 
@@ -84,6 +125,9 @@ private:
     /* Build steps that have no unbuilt dependencies. */
     std::set<Step::ptr> runnable;
 
+    std::mutex runnableMutex;
+    std::condition_variable runnableCV;
+
 public:
     State();
 
@@ -99,21 +143,27 @@ public:
 
     void updateBuild(pqxx::work & txn, Build::ptr build, BuildStatus status);
 
-    void getQueuedBuilds(pqxx::connection & conn);
+    void queueMonitorThreadEntry();
 
-    Step::ptr createStep(const Path & drvPath);
+    void getQueuedBuilds(std::shared_ptr<StoreAPI> store, pqxx::connection & conn);
+
+    Step::ptr createStep(std::shared_ptr<StoreAPI> store, const Path & drvPath);
 
     void destroyStep(Step::ptr step, bool proceed);
 
     /* Get the builds that depend on the given step. */
     std::set<Build::ptr> getDependentBuilds(Step::ptr step);
 
-    void doBuildSteps();
+    void makeRunnable(Step::ptr step);
 
-    void doBuildStep(Step::ptr step);
+    void builderThreadEntry(int slot);
+
+    void doBuildStep(std::shared_ptr<StoreAPI> store, Step::ptr step);
 
     void markSucceededBuild(pqxx::work & txn, Build::ptr build,
         const BuildResult & res, bool isCachedBuild, time_t startTime, time_t stopTime);
+
+    void run();
 };
 
 
@@ -180,8 +230,30 @@ void State::finishBuildStep(pqxx::work & txn, time_t stopTime, BuildID buildId,
 }
 
 
-void State::getQueuedBuilds(pqxx::connection & conn)
+void State::queueMonitorThreadEntry()
 {
+    auto store = openStore(); // FIXME: pool
+
+    Connection conn;
+
+    while (true) {
+        getQueuedBuilds(store, conn);
+
+        {
+            std::unique_lock<std::mutex> lock(exitRequestMutex);
+            exitRequest.wait_for(lock, std::chrono::seconds(5));
+            if (exitRequested) break;
+        }
+    }
+
+    printMsg(lvlError, "queue monitor exits");
+}
+
+
+void State::getQueuedBuilds(std::shared_ptr<StoreAPI> store, pqxx::connection & conn)
+{
+    printMsg(lvlError, "checking the queue...");
+
     pqxx::work txn(conn);
 
     // FIXME: query only builds with ID higher than the previous
@@ -213,10 +285,10 @@ void State::getQueuedBuilds(pqxx::connection & conn)
             continue;
         }
 
-        Step::ptr step = createStep(build->drvPath);
+        Step::ptr step = createStep(store, build->drvPath);
         if (!step) {
             Derivation drv = readDerivation(build->drvPath);
-            BuildResult res = getBuildResult(drv);
+            BuildResult res = getBuildResult(store, drv);
 
             Connection conn;
             pqxx::work txn(conn);
@@ -234,7 +306,7 @@ void State::getQueuedBuilds(pqxx::connection & conn)
 }
 
 
-Step::ptr State::createStep(const Path & drvPath)
+Step::ptr State::createStep(std::shared_ptr<StoreAPI> store, const Path & drvPath)
 {
     auto prev = steps.find(drvPath);
     if (prev != steps.end()) return prev->second;
@@ -262,7 +334,7 @@ Step::ptr State::createStep(const Path & drvPath)
 
     /* Create steps for the dependencies. */
     for (auto & i : step->drv.inputDrvs) {
-        Step::ptr dep = createStep(i.first);
+        Step::ptr dep = createStep(store, i.first);
         if (dep) {
             step->deps.insert(dep);
             dep->rdeps.push_back(step);
@@ -271,7 +343,7 @@ Step::ptr State::createStep(const Path & drvPath)
 
     steps[drvPath] = step;
 
-    if (step->deps.empty()) runnable.insert(step);
+    if (step->deps.empty()) makeRunnable(step);
 
     return step;
 }
@@ -290,7 +362,7 @@ void State::destroyStep(Step::ptr step, bool proceed)
             /* If this rdep has no other dependencies, then we can now
                build it. */
             if (rdep->deps.empty())
-                runnable.insert(rdep);
+                makeRunnable(rdep);
         } else
             /* If ‘step’ failed, then delete all dependent steps as
                well. */
@@ -334,18 +406,43 @@ std::set<Build::ptr> State::getDependentBuilds(Step::ptr step)
 }
 
 
-void State::doBuildSteps()
+void State::makeRunnable(Step::ptr step)
 {
-    while (!runnable.empty()) {
-        printMsg(lvlInfo, format("%1% runnable steps") % runnable.size());
-        Step::ptr step = *runnable.begin();
-        runnable.erase(step);
-        doBuildStep(step);
+    assert(step->deps.empty());
+
+    {
+        std::lock_guard<std::mutex> lock(runnableMutex);
+        runnable.insert(step);
     }
+
+    runnableCV.notify_one();
 }
 
 
-void State::doBuildStep(Step::ptr step)
+void State::builderThreadEntry(int slot)
+{
+    auto store = openStore(); // FIXME: pool
+
+    while (true)  {
+        Step::ptr step;
+        {
+            std::unique_lock<std::mutex> lock(runnableMutex);
+            while (runnable.empty())
+                runnableCV.wait(lock);
+            step = *runnable.begin();
+            runnable.erase(step);
+        }
+
+        printMsg(lvlError, format("slot %1%: got build step ‘%2%’") % slot % step->drvPath);
+
+        doBuildStep(store, step);
+    }
+
+    printMsg(lvlError, "builder thread exits");
+}
+
+
+void State::doBuildStep(std::shared_ptr<StoreAPI> store, Step::ptr step)
 {
     assert(step->deps.empty());
 
@@ -398,7 +495,7 @@ void State::doBuildStep(Step::ptr step)
     time_t stopTime = time(0);
 
     BuildResult res;
-    if (success) res = getBuildResult(step->drv);
+    if (success) res = getBuildResult(store, step->drv);
 
     // FIXME: handle failed-with-output
 
@@ -484,27 +581,45 @@ void State::markSucceededBuild(pqxx::work & txn, Build::ptr build,
 }
 
 
+void State::run()
+{
+    {
+        Connection conn;
+        markActiveBuildStepsAsAborted(conn, 0);
+    }
+
+    queueMonitorThread = std::thread(&State::queueMonitorThreadEntry, this);
+
+    sleep(1);
+
+    for (int n = 0; n < 4; n++)
+        std::thread(&State::builderThreadEntry, this, n).detach();
+
+    queueMonitorThread.join();
+}
+
+
 int main(int argc, char * * argv)
 {
     return handleExceptions(argv[0], [&]() {
         initNix();
 
+        std::thread(signalThread).detach();
+
+        /* Ignore signals. This is inherited by the other threads. */
+        sigset_t set;
+        sigemptyset(&set);
+        sigaddset(&set, SIGHUP);
+        sigaddset(&set, SIGINT);
+        sigaddset(&set, SIGTERM);
+        sigprocmask(SIG_BLOCK, &set, NULL);
+
         settings.buildVerbosity = lvlVomit;
         settings.useSubstitutes = false;
 
-        store = openStore();
-
         /* FIXME: need some locking to prevent multiple instances of
            hydra-queue-runner. */
-
-        Connection conn;
-
         State state;
-
-        state.markActiveBuildStepsAsAborted(conn, 0);
-
-        state.getQueuedBuilds(conn);
-
-        state.doBuildSteps();
+        state.run();
     });
 }