From 7f893b7a43fdca728fd1f7a72e51d31d2a6e7147 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 4 Aug 2010 12:13:58 +0000 Subject: [PATCH] * Allow derivations to hint that they should not be built remotely using the build hook mechanism, by setting the derivation attribute "preferLocalBuild" to true. This has a few use cases: - The user environment builder. Since it just creates a bunch of symlinks without much computation, there is no reason to do it remotely. In fact, doing it remotely requires the entire closure of the user environment to be copied to the remote machine, which is extremely wasteful. - `fetchurl'. Performing the download on a remote machine and then copying it to the local machine involves twice as much network traffic as performing the download locally, and doesn't save any CPU cycles on the local machine. --- corepkgs/buildenv/default.nix | 4 +++ src/libstore/build.cc | 64 ++++++++++++++++++++++------------- 2 files changed, 44 insertions(+), 24 deletions(-) diff --git a/corepkgs/buildenv/default.nix b/corepkgs/buildenv/default.nix index 36dd9d0c6..d76f52740 100644 --- a/corepkgs/buildenv/default.nix +++ b/corepkgs/buildenv/default.nix @@ -11,4 +11,8 @@ derivation { paths = derivations; active = map (x: if x ? meta && x.meta ? active then x.meta.active else "true") derivations; priority = map (x: if x ? meta && x.meta ? priority then x.meta.priority else "5") derivations; + + # Building user environments remotely just causes huge amounts of + # network traffic, so don't do that. + preferLocalBuild = true; } diff --git a/src/libstore/build.cc b/src/libstore/build.cc index 8ce8c873d..5818aa51d 100644 --- a/src/libstore/build.cc +++ b/src/libstore/build.cc @@ -960,6 +960,16 @@ PathSet outputPaths(const DerivationOutputs & outputs) } +static bool canBuildLocally(const string & platform) +{ + return platform == thisSystem +#ifdef CAN_DO_LINUX32_BUILDS + || (platform == "i686-linux" && thisSystem == "x86_64-linux") +#endif + ; +} + + void DerivationGoal::tryToBuild() { trace("trying to build"); @@ -1027,28 +1037,38 @@ void DerivationGoal::tryToBuild() foreach (DerivationOutputs::iterator, i, drv.outputs) if (pathFailed(i->second.path)) return; - /* Is the build hook willing to accept this job? */ - usingBuildHook = true; - switch (tryBuildHook()) { - case rpAccept: - /* Yes, it has started doing so. Wait until we get EOF - from the hook. */ - state = &DerivationGoal::buildDone; - return; - case rpPostpone: - /* Not now; wait until at least one child finishes. */ - worker.waitForAWhile(shared_from_this()); - outputLocks.unlock(); - return; - case rpDecline: - /* We should do it ourselves. */ - break; - } + /* Don't do a remote build if the derivation has the attribute + `preferLocalBuild' set. */ + bool preferLocalBuild = + drv.env["preferLocalBuild"] == "1" && canBuildLocally(drv.platform); + /* Is the build hook willing to accept this job? */ + if (!preferLocalBuild) { + usingBuildHook = true; + switch (tryBuildHook()) { + case rpAccept: + /* Yes, it has started doing so. Wait until we get + EOF from the hook. */ + state = &DerivationGoal::buildDone; + return; + case rpPostpone: + /* Not now; wait until at least one child finishes. */ + worker.waitForAWhile(shared_from_this()); + outputLocks.unlock(); + return; + case rpDecline: + /* We should do it ourselves. */ + break; + } + } + usingBuildHook = false; - /* Make sure that we are allowed to start a build. */ - if (worker.getNrLocalBuilds() >= maxBuildJobs) { + /* Make sure that we are allowed to start a build. If this + derivation prefers to be done locally, do it even if + maxBuildJobs is 0. */ + unsigned int curBuilds = worker.getNrLocalBuilds(); + if (curBuilds >= maxBuildJobs && !(preferLocalBuild && curBuilds == 0)) { worker.waitForBuildSlot(shared_from_this()); outputLocks.unlock(); return; @@ -1379,11 +1399,7 @@ void DerivationGoal::startBuilder() format("building path(s) %1%") % showPaths(outputPaths(drv.outputs))) /* Right platform? */ - if (drv.platform != thisSystem -#ifdef CAN_DO_LINUX32_BUILDS - && !(drv.platform == "i686-linux" && thisSystem == "x86_64-linux") -#endif - ) + if (!canBuildLocally(drv.platform)) throw Error( format("a `%1%' is required to build `%3%', but I am a `%2%'") % drv.platform % thisSystem % drvPath);