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Replace select() with poll() to allow waiting on more than FD_SETSIZE fds

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Dustin DeWeese 2020-04-20 17:32:50 -07:00 committed by Dusty DeWeese
parent 25ed842725
commit c0d940978a
1 changed files with 12 additions and 15 deletions
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27
src/libstore/build.cc
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@ -33,7 +33,6 @@
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/utsname.h>
#include <sys/select.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/un.h>
@ -43,6 +42,7 @@
#include <errno.h>
#include <cstring>
#include <termios.h>
#include <poll.h>
#include <pwd.h>
#include <grp.h>
@ -4789,8 +4789,7 @@ void Worker::waitForInput()
terminated. */
bool useTimeout = false;
struct timeval timeout;
timeout.tv_usec = 0;
long timeout = 0;
auto before = steady_time_point::clock::now();
/* If we're monitoring for silence on stdout/stderr, or if there
@ -4808,7 +4807,7 @@ void Worker::waitForInput()
nearest = std::min(nearest, i.timeStarted + std::chrono::seconds(settings.buildTimeout));
}
if (nearest != steady_time_point::max()) {
timeout.tv_sec = std::max(1L, (long) std::chrono::duration_cast<std::chrono::seconds>(nearest - before).count());
timeout = std::max(1L, (long) std::chrono::duration_cast<std::chrono::seconds>(nearest - before).count());
useTimeout = true;
}
@ -4819,30 +4818,28 @@ void Worker::waitForInput()
if (lastWokenUp == steady_time_point::min())
printError("waiting for locks or build slots...");
if (lastWokenUp == steady_time_point::min() || lastWokenUp > before) lastWokenUp = before;
timeout.tv_sec = std::max(1L,
timeout = std::max(1L,
(long) std::chrono::duration_cast<std::chrono::seconds>(
lastWokenUp + std::chrono::seconds(settings.pollInterval) - before).count());
} else lastWokenUp = steady_time_point::min();
if (useTimeout)
vomit("sleeping %d seconds", timeout.tv_sec);
vomit("sleeping %d seconds", timeout);
/* Use select() to wait for the input side of any logger pipe to
become `available'. Note that `available' (i.e., non-blocking)
includes EOF. */
fd_set fds;
FD_ZERO(&fds);
int fdMax = 0;
std::vector<struct pollfd> pollStatus;
std::map <int, int> fdToPollStatus;
for (auto & i : children) {
for (auto & j : i.fds) {
if (j >= FD_SETSIZE)
throw Error("reached FD_SETSIZE limit");
FD_SET(j, &fds);
if (j >= fdMax) fdMax = j + 1;
pollStatus.push_back((struct pollfd) { .fd = j, .events = POLLIN });
fdToPollStatus[j] = pollStatus.size() - 1;
}
}
if (select(fdMax, &fds, 0, 0, useTimeout ? &timeout : 0) == -1) {
if (poll(pollStatus.data(), pollStatus.size(),
useTimeout ? timeout * 1000 : -1) == -1) {
if (errno == EINTR) return;
throw SysError("waiting for input");
}
@ -4863,7 +4860,7 @@ void Worker::waitForInput()
set<int> fds2(j->fds);
std::vector<unsigned char> buffer(4096);
for (auto & k : fds2) {
if (FD_ISSET(k, &fds)) {
if (pollStatus.at(fdToPollStatus.at(k)).revents) {
ssize_t rd = read(k, buffer.data(), buffer.size());
// FIXME: is there a cleaner way to handle pt close
// than EIO? Is this even standard?