diff options
| -rw-r--r-- | src/nix-env/nix-env.cc | 301 |
1 files changed, 163 insertions, 138 deletions
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc index fa053d3484..6cbd06f8d2 100644 --- a/src/nix-env/nix-env.cc +++ b/src/nix-env/nix-env.cc @@ -215,8 +215,34 @@ static DrvInfos queryInstalled(EvalState & state, const Path & userEnv) } -static void createUserEnv(EvalState & state, const DrvInfos & elems, - const Path & profile, bool keepDerivations) +/* Ensure exclusive access to a profile. Any command that modifies + the profile first acquires this lock. */ +static void lockProfile(PathLocks & lock, const Path & profile) +{ + lock.lockPaths(singleton<PathSet>(profile), + (format("waiting for lock on profile `%1%'") % profile).str()); + lock.setDeletion(true); +} + + +/* Optimistic locking is used by long-running operations like `nix-env + -i'. Instead of acquiring the exclusive lock for the entire + duration of the operation, we just perform the operation + optimistically (without an exclusive lock), and check at the end + whether the profile changed while we were busy (i.e., the symlink + target changed). If so, the operation is restarted. Restarting is + generally cheap, since the build results are still in the Nix + store. Most of the time, only the user environment has to be + rebuilt. */ +static string optimisticLockProfile(const Path & profile) +{ + return pathExists(profile) ? readLink(profile) : ""; +} + + +static bool createUserEnv(EvalState & state, const DrvInfos & elems, + const Path & profile, bool keepDerivations, + const string & lockToken) { /* Build the components in the user environment, if they don't exist already. */ @@ -305,9 +331,20 @@ static void createUserEnv(EvalState & state, const DrvInfos & elems, store->buildDerivations(singleton<PathSet>(topLevelDrv.queryDrvPath(state))); /* Switch the current user environment to the output path. */ + PathLocks lock; + lockProfile(lock, profile); + + Path lockTokenCur = optimisticLockProfile(profile); + if (lockToken != lockTokenCur) { + printMsg(lvlError, format("profile `%1%' changed while we were busy; restarting") % profile); + return false; + } + debug(format("switching to new user environment")); Path generation = createGeneration(profile, topLevelDrv.queryOutPath(state)); switchLink(profile, generation); + + return true; } @@ -544,14 +581,6 @@ static void printMissing(EvalState & state, const DrvInfos & elems) } -static void lockProfile(PathLocks & lock, const Path & profile) -{ - lock.lockPaths(singleton<PathSet>(profile), - (format("waiting for lock on profile `%1%'") % profile).str()); - lock.setDeletion(true); -} - - static void installDerivations(Globals & globals, const Strings & args, const Path & profile) { @@ -574,35 +603,35 @@ static void installDerivations(Globals & globals, /* Add in the already installed derivations, unless they have the same name as a to-be-installed element. */ - PathLocks lock; - lockProfile(lock, profile); - DrvInfos installedElems = queryInstalled(globals.state, profile); - DrvInfos allElems(newElems); - for (DrvInfos::iterator i = installedElems.begin(); - i != installedElems.end(); ++i) - { - DrvName drvName(i->name); - MetaInfo meta = i->queryMetaInfo(globals.state); - if (!globals.preserveInstalled && - newNames.find(drvName.name) != newNames.end() && - meta["keep"] != "true") - printMsg(lvlInfo, - format("replacing old `%1%'") % i->name); - else - allElems.push_back(*i); - } + while (true) { + string lockToken = optimisticLockProfile(profile); + + DrvInfos installedElems = queryInstalled(globals.state, profile); + + DrvInfos allElems(newElems); + foreach (DrvInfos::iterator, i, installedElems) { + DrvName drvName(i->name); + MetaInfo meta = i->queryMetaInfo(globals.state); + if (!globals.preserveInstalled && + newNames.find(drvName.name) != newNames.end() && + meta["keep"] != "true") + printMsg(lvlInfo, + format("replacing old `%1%'") % i->name); + else + allElems.push_back(*i); + } - for (DrvInfos::iterator i = newElems.begin(); i != newElems.end(); ++i) - printMsg(lvlInfo, - format("installing `%1%'") % i->name); + foreach (DrvInfos::iterator, i, newElems) + printMsg(lvlInfo, format("installing `%1%'") % i->name); - printMissing(globals.state, newElems); + printMissing(globals.state, newElems); - if (globals.dryRun) return; + if (globals.dryRun) return; - createUserEnv(globals.state, allElems, - profile, globals.keepDerivations); + if (createUserEnv(globals.state, allElems, + profile, globals.keepDerivations, lockToken)) break; + } } @@ -634,77 +663,75 @@ static void upgradeDerivations(Globals & globals, for a derivation in the input Nix expression that has the same name and a higher version number. */ - /* Load the currently installed derivations. */ - PathLocks lock; - lockProfile(lock, globals.profile); - DrvInfos installedElems = queryInstalled(globals.state, globals.profile); + while (true) { + string lockToken = optimisticLockProfile(globals.profile); + + DrvInfos installedElems = queryInstalled(globals.state, globals.profile); - /* Fetch all derivations from the input file. */ - DrvInfos availElems; - queryInstSources(globals.state, globals.instSource, args, availElems, false); + /* Fetch all derivations from the input file. */ + DrvInfos availElems; + queryInstSources(globals.state, globals.instSource, args, availElems, false); - /* Go through all installed derivations. */ - DrvInfos newElems; - for (DrvInfos::iterator i = installedElems.begin(); - i != installedElems.end(); ++i) - { - DrvName drvName(i->name); + /* Go through all installed derivations. */ + DrvInfos newElems; + foreach (DrvInfos::iterator, i, installedElems) { + DrvName drvName(i->name); - MetaInfo meta = i->queryMetaInfo(globals.state); - if (meta["keep"] == "true") { - newElems.push_back(*i); - continue; - } + MetaInfo meta = i->queryMetaInfo(globals.state); + if (meta["keep"] == "true") { + newElems.push_back(*i); + continue; + } - /* Find the derivation in the input Nix expression with the - same name that satisfies the version constraints specified - by upgradeType. If there are multiple matches, take the - one with the highest priority. If there are still multiple - matches, take the one with the highest version. */ - DrvInfos::iterator bestElem = availElems.end(); - DrvName bestName; - for (DrvInfos::iterator j = availElems.begin(); - j != availElems.end(); ++j) - { - DrvName newName(j->name); - if (newName.name == drvName.name) { - int d = comparePriorities(globals.state, *i, *j); - if (d == 0) d = compareVersions(drvName.version, newName.version); - if (upgradeType == utLt && d < 0 || - upgradeType == utLeq && d <= 0 || - upgradeType == utEq && d == 0 || - upgradeType == utAlways) - { - int d2 = -1; - if (bestElem != availElems.end()) { - d2 = comparePriorities(globals.state, *bestElem, *j); - if (d2 == 0) d2 = compareVersions(bestName.version, newName.version); - } - if (d2 < 0) { - bestElem = j; - bestName = newName; + /* Find the derivation in the input Nix expression with + the same name that satisfies the version constraints + specified by upgradeType. If there are multiple + matches, take the one with the highest priority. If + there are still multiple matches, take the one with the + highest version. */ + DrvInfos::iterator bestElem = availElems.end(); + DrvName bestName; + foreach (DrvInfos::iterator, j, availElems) { + DrvName newName(j->name); + if (newName.name == drvName.name) { + int d = comparePriorities(globals.state, *i, *j); + if (d == 0) d = compareVersions(drvName.version, newName.version); + if (upgradeType == utLt && d < 0 || + upgradeType == utLeq && d <= 0 || + upgradeType == utEq && d == 0 || + upgradeType == utAlways) + { + int d2 = -1; + if (bestElem != availElems.end()) { + d2 = comparePriorities(globals.state, *bestElem, *j); + if (d2 == 0) d2 = compareVersions(bestName.version, newName.version); + } + if (d2 < 0) { + bestElem = j; + bestName = newName; + } } } } - } - if (bestElem != availElems.end() && - i->queryOutPath(globals.state) != + if (bestElem != availElems.end() && + i->queryOutPath(globals.state) != bestElem->queryOutPath(globals.state)) - { - printMsg(lvlInfo, - format("upgrading `%1%' to `%2%'") - % i->name % bestElem->name); - newElems.push_back(*bestElem); - } else newElems.push_back(*i); - } + { + printMsg(lvlInfo, + format("upgrading `%1%' to `%2%'") + % i->name % bestElem->name); + newElems.push_back(*bestElem); + } else newElems.push_back(*i); + } - printMissing(globals.state, newElems); + printMissing(globals.state, newElems); - if (globals.dryRun) return; + if (globals.dryRun) return; - createUserEnv(globals.state, newElems, - globals.profile, globals.keepDerivations); + if (createUserEnv(globals.state, newElems, + globals.profile, globals.keepDerivations, lockToken)) break; + } } @@ -748,29 +775,27 @@ static void opSetFlag(Globals & globals, string flagValue = *arg++; DrvNames selectors = drvNamesFromArgs(Strings(arg, opArgs.end())); - /* Load the currently installed derivations. */ - PathLocks lock; - lockProfile(lock, globals.profile); - DrvInfos installedElems = queryInstalled(globals.state, globals.profile); + while (true) { + string lockToken = optimisticLockProfile(globals.profile); - /* Update all matching derivations. */ - for (DrvInfos::iterator i = installedElems.begin(); - i != installedElems.end(); ++i) - { - DrvName drvName(i->name); - for (DrvNames::iterator j = selectors.begin(); - j != selectors.end(); ++j) - if (j->matches(drvName)) { - printMsg(lvlInfo, - format("setting flag on `%1%'") % i->name); - setMetaFlag(globals.state, *i, flagName, flagValue); - break; - } - } + DrvInfos installedElems = queryInstalled(globals.state, globals.profile); + + /* Update all matching derivations. */ + foreach (DrvInfos::iterator, i, installedElems) { + DrvName drvName(i->name); + foreach (DrvNames::iterator, j, selectors) + if (j->matches(drvName)) { + printMsg(lvlInfo, + format("setting flag on `%1%'") % i->name); + setMetaFlag(globals.state, *i, flagName, flagValue); + break; + } + } - /* Write the new user environment. */ - createUserEnv(globals.state, installedElems, - globals.profile, globals.keepDerivations); + /* Write the new user environment. */ + if (createUserEnv(globals.state, installedElems, + globals.profile, globals.keepDerivations, lockToken)) break; + } } @@ -812,33 +837,33 @@ static void opSet(Globals & globals, static void uninstallDerivations(Globals & globals, Strings & selectors, Path & profile) { - PathLocks lock; - lockProfile(lock, profile); - DrvInfos installedElems = queryInstalled(globals.state, profile); - DrvInfos newElems; + while (true) { + string lockToken = optimisticLockProfile(profile); - for (DrvInfos::iterator i = installedElems.begin(); - i != installedElems.end(); ++i) - { - DrvName drvName(i->name); - bool found = false; - for (Strings::iterator j = selectors.begin(); j != selectors.end(); ++j) - /* !!! the repeated calls to followLinksToStorePath() are - expensive, should pre-compute them. */ - if ((isPath(*j) && i->queryOutPath(globals.state) == followLinksToStorePath(*j)) - || DrvName(*j).matches(drvName)) - { - printMsg(lvlInfo, format("uninstalling `%1%'") % i->name); - found = true; - break; - } - if (!found) newElems.push_back(*i); - } + DrvInfos installedElems = queryInstalled(globals.state, profile); + DrvInfos newElems; - if (globals.dryRun) return; + foreach (DrvInfos::iterator, i, installedElems) { + DrvName drvName(i->name); + bool found = false; + foreach (Strings::iterator, j, selectors) + /* !!! the repeated calls to followLinksToStorePath() + are expensive, should pre-compute them. */ + if ((isPath(*j) && i->queryOutPath(globals.state) == followLinksToStorePath(*j)) + || DrvName(*j).matches(drvName)) + { + printMsg(lvlInfo, format("uninstalling `%1%'") % i->name); + found = true; + break; + } + if (!found) newElems.push_back(*i); + } - createUserEnv(globals.state, newElems, - profile, globals.keepDerivations); + if (globals.dryRun) return; + + if (createUserEnv(globals.state, newElems, + profile, globals.keepDerivations, lockToken)) break; + } } |