diff options
Diffstat (limited to 'src/libstore/build.cc')
| -rw-r--r-- | src/libstore/build.cc | 96 |
1 files changed, 86 insertions, 10 deletions
diff --git a/src/libstore/build.cc b/src/libstore/build.cc index 4a2affdf59..5ad8105006 100644 --- a/src/libstore/build.cc +++ b/src/libstore/build.cc @@ -181,6 +181,9 @@ private: WeakGoalMap derivationGoals; WeakGoalMap substitutionGoals; + /* Goals waiting for busy paths to be unlocked. */ + WeakGoals waitingForAnyGoal; + public: Worker(); @@ -222,6 +225,10 @@ public: get info about `storePath' (with --query-info). We combine substituter invocations to reduce overhead. */ void waitForInfo(GoalPtr goal, Path sub, Path storePath); + + /* Wait for any goal to finish. Pretty indiscriminate way to + wait for some resource that some other goal is holding. */ + void waitForAnyGoal(GoalPtr goal); /* Loop until the specified top-level goals have finished. */ void run(const Goals & topGoals); @@ -642,7 +649,7 @@ private: void buildDone(); /* Is the build hook willing to perform the build? */ - typedef enum {rpAccept, rpDecline, rpPostpone, rpDone} HookReply; + typedef enum {rpAccept, rpDecline, rpPostpone, rpDone, rpRestart} HookReply; HookReply tryBuildHook(); /* Synchronously wait for a build hook to finish. */ @@ -651,9 +658,13 @@ private: /* Acquires locks on the output paths and gathers information about the build (e.g., the input closures). During this process its possible that we find out that the build is - unnecessary, in which case we return false (this is not an - error condition!). */ - bool prepareBuild(); + unnecessary, in which case we return prDone. It's also + possible that some other goal is already building/substituting + the output paths, in which case we return prRestart (go back to + the haveDerivation() state). Otherwise, prProceed is + returned. */ + typedef enum {prProceed, prDone, prRestart} PrepareBuildReply; + PrepareBuildReply prepareBuild(); /* Start building a derivation. */ void startBuilder(); @@ -791,6 +802,20 @@ void DerivationGoal::haveDerivation() return; } + /* If this is a fixed-output derivation, it is possible that some + other goal is already building the output paths. (The case + where some other process is building it is handled through + normal locking mechanisms.) So if any output paths are already + being built, put this goal to sleep. */ + for (PathSet::iterator i = invalidOutputs.begin(); + i != invalidOutputs.end(); ++i) + if (pathIsLockedByMe(*i)) { + /* Wait until any goal finishes (hopefully the one that is + locking *i), then retry haveDerivation(). */ + worker.waitForAnyGoal(shared_from_this()); + return; + } + /* We are first going to try to create the invalid output paths through substitutes. If that doesn't work, we'll build them. */ @@ -884,6 +909,12 @@ void DerivationGoal::tryToBuild() /* Somebody else did it. */ amDone(ecSuccess); return; + case rpRestart: + /* Somebody else is building this output path. + Restart from haveDerivation(). */ + state = &DerivationGoal::haveDerivation; + worker.waitForAnyGoal(shared_from_this()); + return; } /* Make sure that we are allowed to start a build. */ @@ -894,9 +925,14 @@ void DerivationGoal::tryToBuild() /* Acquire locks and such. If we then see that the build has been done by somebody else, we're done. */ - if (!prepareBuild()) { + PrepareBuildReply preply = prepareBuild(); + if (preply == prDone) { amDone(ecSuccess); return; + } else if (preply == prRestart) { + state = &DerivationGoal::haveDerivation; + worker.waitForAnyGoal(shared_from_this()); + return; } /* Okay, we have to build. */ @@ -1176,11 +1212,12 @@ DerivationGoal::HookReply DerivationGoal::tryBuildHook() /* Acquire locks and such. If we then see that the output paths are now valid, we're done. */ - if (!prepareBuild()) { + PrepareBuildReply preply = prepareBuild(); + if (preply == prDone || preply == prRestart) { /* Tell the hook to exit. */ writeLine(toHook.writeSide, "cancel"); terminateBuildHook(); - return rpDone; + return preply == prDone ? rpDone : rpRestart; } printMsg(lvlInfo, format("running hook to build path(s) %1%") @@ -1256,8 +1293,20 @@ void DerivationGoal::terminateBuildHook(bool kill) } -bool DerivationGoal::prepareBuild() +DerivationGoal::PrepareBuildReply DerivationGoal::prepareBuild() { + /* Check for the possibility that some other goal in this process + has locked the output since we checked in haveDerivation(). + (It can't happen between here and the lockPaths() call below + because we're not allowing multi-threading.) */ + for (DerivationOutputs::iterator i = drv.outputs.begin(); + i != drv.outputs.end(); ++i) + if (pathIsLockedByMe(i->second.path)) { + debug(format("restarting derivation `%1%' because `%2%' is locked by another goal") + % drvPath % i->second.path); + return prRestart; + } + /* Obtain locks on all output paths. The locks are automatically released when we exit this function or Nix crashes. */ /* !!! BUG: this could block, which is not allowed. */ @@ -1276,7 +1325,7 @@ bool DerivationGoal::prepareBuild() debug(format("skipping build of derivation `%1%', someone beat us to it") % drvPath); outputLocks.setDeletion(true); - return false; + return prDone; } if (validPaths.size() > 0) { @@ -1341,7 +1390,7 @@ bool DerivationGoal::prepareBuild() allPaths.insert(inputPaths.begin(), inputPaths.end()); - return true; + return prProceed; } @@ -2028,6 +2077,16 @@ void SubstitutionGoal::tryToRun() return; } + /* Maybe a derivation goal has already locked this path + (exceedingly unlikely, since it should have used a substitute + first, but let's be defensive). */ + if (pathIsLockedByMe(storePath)) { + debug(format("restarting substitution of `%1%' because it's locked by another goal") + % storePath); + worker.waitForAnyGoal(shared_from_this()); + return; /* restart in the tryToRun() state when another goal finishes */ + } + /* Acquire a lock on the output path. */ outputLock = boost::shared_ptr<PathLocks>(new PathLocks); outputLock->lockPaths(singleton<PathSet>(storePath), @@ -2251,6 +2310,16 @@ void Worker::removeGoal(GoalPtr goal) if (goal->getExitCode() == Goal::ecFailed && !keepGoing) topGoals.clear(); } + + /* Wake up goals waiting for any goal to finish. */ + for (WeakGoals::iterator i = waitingForAnyGoal.begin(); + i != waitingForAnyGoal.end(); ++i) + { + GoalPtr goal = i->lock(); + if (goal) wakeUp(goal); + } + + waitingForAnyGoal.clear(); } @@ -2337,6 +2406,13 @@ void Worker::waitForInfo(GoalPtr goal, Path sub, Path storePath) } +void Worker::waitForAnyGoal(GoalPtr goal) +{ + debug("wait for any goal"); + waitingForAnyGoal.insert(goal); +} + + void Worker::getInfo() { for (map<Path, PathSet>::iterator i = requestedInfo.begin(); |