From 69326f3637f1560407711838e7298d736274ffd4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 4 Nov 2019 14:27:28 +0100
Subject: [PATCH] Recursive Nix: Handle concurrent client connections

---
 src/libstore/build.cc | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index e77512ca4..63557b560 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -895,6 +895,9 @@ private:
     /* The daemon main thread. */
     std::thread daemonThread;
 
+    /* The daemon worker threads. */
+    std::vector<std::thread> daemonWorkerThreads;
+
     /* Paths that were added via recursive Nix calls. */
     PathSet addedPaths;
 
@@ -2875,17 +2878,19 @@ void DerivationGoal::startDaemon()
 
             debug("received daemon connection");
 
-            // FIXME: process on a separate thread.
-            FdSource from(remote.get());
-            FdSink to(remote.get());
-            try {
-                daemon::processConnection(store, from, to,
-                    daemon::NotTrusted, daemon::Recursive, "nobody", 65535);
-            } catch (SysError &) {
-                ignoreException();
-            }
+            auto workerThread = std::thread([this, store, remote{std::move(remote)}]() {
+                FdSource from(remote.get());
+                FdSink to(remote.get());
+                try {
+                    daemon::processConnection(store, from, to,
+                        daemon::NotTrusted, daemon::Recursive, "nobody", 65535);
+                    debug("terminated daemon connection");
+                } catch (SysError &) {
+                    ignoreException();
+                }
+            });
 
-            debug("terminated daemon connection");
+            daemonWorkerThreads.push_back(std::move(workerThread));
         }
 
         debug("daemon shutting down");
@@ -2901,6 +2906,12 @@ void DerivationGoal::stopDaemon()
     if (daemonThread.joinable())
         daemonThread.join();
 
+    // FIXME: should prune worker threads more quickly.
+    // FIXME: shutdown the client socket to speed up worker termination.
+    for (auto & thread : daemonWorkerThreads)
+        thread.join();
+    daemonWorkerThreads.clear();
+
     daemonSocket = -1;
 }