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* Re-enable build hooks.

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This commit is contained in:
Eelco Dolstra 2004-06-19 21:45:04 +00:00
parent 41ec982f31
commit 23bb902d1f
2 changed files with 335 additions and 83 deletions
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413
src/libstore/normalise.cc
View file

@ -81,7 +81,14 @@ public:
/* A mapping used to remember for each child process to what goal it
belongs, and a file descriptor for receiving log data. */
typedef map<pid_t, pair<int, GoalPtr> > Children;
struct Child
{
GoalPtr goal;
int fdOutput;
bool inBuildSlot;
};
typedef map<pid_t, Child> Children;
/* The worker class. */
@ -101,6 +108,10 @@ private:
/* Child processes currently running. */
Children children;
/* Number of build slots occupied. Not all child processes
(namely build hooks) count as occupied build slots. */
unsigned int nrChildren;
/* Maps used to prevent multiple instantiation of a goal for the
same expression / path. */
GoalMap normalisationGoals;
@ -130,7 +141,8 @@ public:
bool canBuildMore();
/* Registers / unregisters a running child process. */
void childStarted(GoalPtr goal, pid_t pid, int fdLogFile);
void childStarted(GoalPtr goal, pid_t pid, int fdOutput,
bool inBuildSlot);
void childTerminated(pid_t pid);
/* Add a goal to the set of goals waiting for a build slot. */
@ -227,7 +239,8 @@ public:
~NormalisationGoal();
void work();
private:
/* The states. */
void init();
void haveStoreExpr();
@ -236,6 +249,20 @@ public:
void tryToBuild();
void buildDone();
/* Is the build hook willing to perform the build? */
typedef enum {rpAccept, rpDecline, rpPostpone, rpDone} HookReply;
HookReply tryBuildHook();
/* Synchronously wait for a build hook to finish. */
void terminateBuildHook();
/* 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();
/* Start building a derivation. */
void startBuilder();
@ -382,9 +409,11 @@ void NormalisationGoal::inputRealised()
{
debug(format("all inputs realised of `%1%'") % nePath);
/* Now wait until a build slot becomes available. */
/* Okay, try to build. Note that here we don't wait for a build
slot to become available, since we don't need one if there is a
build hook. */
state = &NormalisationGoal::tryToBuild;
worker.waitForBuildSlot(shared_from_this());
worker.wakeUp(shared_from_this());
}
@ -392,79 +421,35 @@ void NormalisationGoal::tryToBuild()
{
debug(format("trying to build `%1%'") % nePath);
/* Is the build hook willing to accept this job? */
switch (tryBuildHook()) {
case rpAccept:
/* Yes, it has started doing so. Wait until we get
EOF from the hook. */
state = &NormalisationGoal::buildDone;
return;
case rpPostpone:
/* Not now; wait until at least one child finishes. */
worker.waitForBuildSlot(shared_from_this());
return;
case rpDecline:
/* We should do it ourselves. */
break;
case rpDone:
/* Somebody else did it (there is a successor now). */
amDone();
return;
}
/* Make sure that we are allowed to start a build. */
if (!worker.canBuildMore()) {
worker.waitForBuildSlot(shared_from_this());
return;
}
/* 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. */
outputLocks.lockPaths(expr.derivation.outputs);
/* Now check again whether there is a successor. This is because
another process may have started building in parallel. After
it has finished and released the locks, we can (and should)
reuse its results. (Strictly speaking the first successor
check can be omitted, but that would be less efficient.) Note
that since we now hold the locks on the output paths, no other
process can build this expression, so no further checks are
necessary. */
Path nfPath;
if (querySuccessor(nePath, nfPath)) {
debug(format("skipping build of expression `%1%', someone beat us to it")
% nePath);
outputLocks.setDeletion(true);
amDone();
return;
}
/* Gather information necessary for computing the closure and/or
running the build hook. */
/* The outputs are referenceable paths. */
for (PathSet::iterator i = expr.derivation.outputs.begin();
i != expr.derivation.outputs.end(); ++i)
{
debug(format("building path `%1%'") % *i);
allPaths.insert(*i);
}
/* Get information about the inputs (these all exist now). */
for (PathSet::iterator i = expr.derivation.inputs.begin();
i != expr.derivation.inputs.end(); ++i)
{
checkInterrupt();
Path nePath = *i, nfPath;
if (!querySuccessor(nePath, nfPath)) nfPath = nePath;
inputNFs.insert(nfPath);
if (nfPath != nePath) inputSucs[nePath] = nfPath;
/* !!! nfPath should be a root of the garbage collector while
we are building */
StoreExpr ne = storeExprFromPath(nfPath);
if (ne.type != StoreExpr::neClosure) abort();
for (ClosureElems::iterator j = ne.closure.elems.begin();
j != ne.closure.elems.end(); ++j)
{
inClosures[j->first] = j->second;
allPaths.insert(j->first);
}
}
/* We can skip running the builder if all output paths are already
valid. */
bool fastBuild = true;
for (PathSet::iterator i = expr.derivation.outputs.begin();
i != expr.derivation.outputs.end(); ++i)
if (!isValidPath(*i)) {
fastBuild = false;
break;
}
if (fastBuild) {
printMsg(lvlChatty, format("skipping build; output paths already exist"));
createClosure();
/* Acquire locks and such. If we then see that there now is a
successor, we're done. */
if (!prepareBuild()) {
amDone();
return;
}
@ -527,6 +512,260 @@ void NormalisationGoal::buildDone()
}
static string readLine(int fd)
{
string s;
while (1) {
char ch;
ssize_t rd = read(fd, &ch, 1);
if (rd == -1) {
if (errno != EINTR)
throw SysError("reading a line");
} else if (rd == 0)
throw Error("unexpected EOF reading a line");
else {
if (ch == '\n') return s;
s += ch;
}
}
}
static void writeLine(int fd, string s)
{
s += '\n';
writeFull(fd, (const unsigned char *) s.c_str(), s.size());
}
/* !!! ugly hack */
static void drain(int fd)
{
unsigned char buffer[1024];
while (1) {
ssize_t rd = read(fd, buffer, sizeof buffer);
if (rd == -1) {
if (errno != EINTR)
throw SysError("draining");
} else if (rd == 0) break;
else writeFull(STDERR_FILENO, buffer, rd);
}
}
NormalisationGoal::HookReply NormalisationGoal::tryBuildHook()
{
Path buildHook = getEnv("NIX_BUILD_HOOK");
if (buildHook == "") return rpDecline;
buildHook = absPath(buildHook);
/* Create a directory where we will store files used for
communication between us and the build hook. */
tmpDir = createTempDir();
/* Create the log file and pipe. */
openLogFile();
/* Create the communication pipes. */
toHook.create();
fromHook.create();
/* Fork the hook. */
switch (pid = fork()) {
case -1:
throw SysError("unable to fork");
case 0:
try { /* child */
initChild();
execl(buildHook.c_str(), buildHook.c_str(),
(worker.canBuildMore() ? (string) "1" : "0").c_str(),
thisSystem.c_str(),
expr.derivation.platform.c_str(),
nePath.c_str(), 0);
throw SysError(format("executing `%1%'") % buildHook);
} catch (exception & e) {
cerr << format("build error: %1%\n") % e.what();
}
_exit(1);
}
/* parent */
logPipe.writeSide.close();
worker.childStarted(shared_from_this(),
pid, logPipe.readSide, false);
fromHook.writeSide.close();
toHook.readSide.close();
/* Read the first line of input, which should be a word indicating
whether the hook wishes to perform the build. !!! potential
for deadlock here: we should also read from the child's logger
pipe. */
string reply;
try {
reply = readLine(fromHook.readSide);
} catch (Error & e) {
drain(logPipe.readSide);
throw;
}
debug(format("hook reply is `%1%'") % reply);
if (reply == "decline" || reply == "postpone") {
/* Clean up the child. !!! hacky / should verify */
drain(logPipe.readSide);
terminateBuildHook();
return reply == "decline" ? rpDecline : rpPostpone;
}
else if (reply == "accept") {
/* Acquire locks and such. If we then see that there now is a
successor, we're done. */
if (!prepareBuild()) {
writeLine(toHook.writeSide, "cancel");
terminateBuildHook();
return rpDone;
}
/* Write the information that the hook needs to perform the
build, i.e., the set of input paths (including closure
expressions), the set of output paths, and the successor
mappings for the input expressions. */
Path inputListFN = tmpDir + "/inputs";
Path outputListFN = tmpDir + "/outputs";
Path successorsListFN = tmpDir + "/successors";
string s;
for (ClosureElems::iterator i = inClosures.begin();
i != inClosures.end(); ++i)
s += i->first + "\n";
for (PathSet::iterator i = inputNFs.begin();
i != inputNFs.end(); ++i)
s += *i + "\n";
writeStringToFile(inputListFN, s);
s = "";
for (PathSet::iterator i = expr.derivation.outputs.begin();
i != expr.derivation.outputs.end(); ++i)
s += *i + "\n";
writeStringToFile(outputListFN, s);
s = "";
for (map<Path, Path>::iterator i = inputSucs.begin();
i != inputSucs.end(); ++i)
s += i->first + " " + i->second + "\n";
writeStringToFile(successorsListFN, s);
writeLine(toHook.writeSide, "okay");
inHook = true;
return rpAccept;
}
else throw Error(format("bad hook reply `%1%'") % reply);
}
void NormalisationGoal::terminateBuildHook()
{
/* !!! drain stdout of hook */
debug("terminating build hook");
int status;
if (waitpid(pid, &status, 0) != pid)
printMsg(lvlError, format("process `%1%' missing") % pid);
worker.childTerminated(pid);
pid = -1;
fromHook.readSide.close();
toHook.writeSide.close();
fdLogFile.close();
logPipe.readSide.close();
}
bool NormalisationGoal::prepareBuild()
{
/* 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. */
outputLocks.lockPaths(expr.derivation.outputs);
/* Now check again whether there is a successor. This is because
another process may have started building in parallel. After
it has finished and released the locks, we can (and should)
reuse its results. (Strictly speaking the first successor
check can be omitted, but that would be less efficient.) Note
that since we now hold the locks on the output paths, no other
process can build this expression, so no further checks are
necessary. */
Path nfPath;
if (querySuccessor(nePath, nfPath)) {
debug(format("skipping build of expression `%1%', someone beat us to it")
% nePath);
outputLocks.setDeletion(true);
return false;
}
/* Gather information necessary for computing the closure and/or
running the build hook. */
/* The outputs are referenceable paths. */
for (PathSet::iterator i = expr.derivation.outputs.begin();
i != expr.derivation.outputs.end(); ++i)
{
debug(format("building path `%1%'") % *i);
allPaths.insert(*i);
}
/* Get information about the inputs (these all exist now). */
for (PathSet::iterator i = expr.derivation.inputs.begin();
i != expr.derivation.inputs.end(); ++i)
{
checkInterrupt();
Path nePath = *i, nfPath;
if (!querySuccessor(nePath, nfPath)) nfPath = nePath;
inputNFs.insert(nfPath);
if (nfPath != nePath) inputSucs[nePath] = nfPath;
/* !!! nfPath should be a root of the garbage collector while
we are building */
StoreExpr ne = storeExprFromPath(nfPath);
if (ne.type != StoreExpr::neClosure) abort();
for (ClosureElems::iterator j = ne.closure.elems.begin();
j != ne.closure.elems.end(); ++j)
{
inClosures[j->first] = j->second;
allPaths.insert(j->first);
}
}
/* We can skip running the builder if all output paths are already
valid. */
bool fastBuild = true;
for (PathSet::iterator i = expr.derivation.outputs.begin();
i != expr.derivation.outputs.end(); ++i)
if (!isValidPath(*i)) {
fastBuild = false;
break;
}
if (fastBuild) {
printMsg(lvlChatty, format("skipping build; output paths already exist"));
createClosure();
return false;
}
return true;
}
void NormalisationGoal::startBuilder()
{
/* Right platform? */
@ -648,7 +887,8 @@ void NormalisationGoal::startBuilder()
/* parent */
logPipe.writeSide.close();
worker.childStarted(shared_from_this(), pid, logPipe.readSide);
worker.childStarted(shared_from_this(),
pid, logPipe.readSide, true);
}
@ -1083,19 +1323,32 @@ void Worker::wakeUp(GoalPtr goal)
bool Worker::canBuildMore()
{
return children.size() < maxBuildJobs;
return nrChildren < maxBuildJobs;
}
void Worker::childStarted(GoalPtr goal, pid_t pid, int fdLogFile)
void Worker::childStarted(GoalPtr goal,
pid_t pid, int fdOutput, bool inBuildSlot)
{
children[pid] = pair<int, GoalPtr>(fdLogFile, goal);
Child child;
child.goal = goal;
child.fdOutput = fdOutput;
child.inBuildSlot = inBuildSlot;
children[pid] = child;
if (inBuildSlot) nrChildren++;
}
void Worker::childTerminated(pid_t pid)
{
assert(children.find(pid) != children.end());
Children::iterator i = children.find(pid);
assert(i != children.end());
if (i->second.inBuildSlot) {
assert(nrChildren > 0);
nrChildren--;
}
children.erase(pid);
/* Wake up goals waiting for a build slot. */
@ -1170,7 +1423,7 @@ void Worker::waitForInput()
for (Children::iterator i = children.begin();
i != children.end(); ++i)
{
int fd = i->second.first;
int fd = i->second.fdOutput;
FD_SET(fd, &fds);
if (fd >= fdMax) fdMax = fd + 1;
}
@ -1185,8 +1438,8 @@ void Worker::waitForInput()
i != children.end(); ++i)
{
checkInterrupt();
GoalPtr goal = i->second.second;
int fd = i->second.first;
GoalPtr goal = i->second.goal;
int fd = i->second.fdOutput;
if (FD_ISSET(fd, &fds)) {
unsigned char buffer[4096];
ssize_t rd = read(fd, buffer, sizeof(buffer));

5
tests/Makefile.am
View file

@ -18,9 +18,8 @@ locking.sh: locking.nix
parallel.sh: parallel.nix
build-hook.sh: build-hook.nix
#TESTS = init.sh simple.sh dependencies.sh locking.sh parallel.sh \
# build-hook.sh
TESTS = init.sh build-hook.sh
TESTS = init.sh simple.sh dependencies.sh locking.sh parallel.sh \
build-hook.sh
XFAIL_TESTS =