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Merge pull request #3522 from HackerFoo/replace-select-with-poll

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Replace select() with poll()
This commit is contained in:
Eelco Dolstra 2020-04-22 12:25:41 +02:00 committed by GitHub
commit 4a2a45f53d
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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/types.h>
#include <sys/stat.h> #include <sys/stat.h>
#include <sys/utsname.h> #include <sys/utsname.h>
#include <sys/select.h>
#include <sys/resource.h> #include <sys/resource.h>
#include <sys/socket.h> #include <sys/socket.h>
#include <sys/un.h> #include <sys/un.h>
@ -43,6 +42,7 @@
#include <errno.h> #include <errno.h>
#include <cstring> #include <cstring>
#include <termios.h> #include <termios.h>
#include <poll.h>
#include <pwd.h> #include <pwd.h>
#include <grp.h> #include <grp.h>
@ -4789,8 +4789,7 @@ void Worker::waitForInput()
terminated. */ terminated. */
bool useTimeout = false; bool useTimeout = false;
struct timeval timeout; long timeout = 0;
timeout.tv_usec = 0;
auto before = steady_time_point::clock::now(); auto before = steady_time_point::clock::now();
/* If we're monitoring for silence on stdout/stderr, or if there /* 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)); nearest = std::min(nearest, i.timeStarted + std::chrono::seconds(settings.buildTimeout));
} }
if (nearest != steady_time_point::max()) { 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; useTimeout = true;
} }
@ -4819,30 +4818,28 @@ void Worker::waitForInput()
if (lastWokenUp == steady_time_point::min()) if (lastWokenUp == steady_time_point::min())
printError("waiting for locks or build slots..."); printError("waiting for locks or build slots...");
if (lastWokenUp == steady_time_point::min() || lastWokenUp > before) lastWokenUp = before; 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>( (long) std::chrono::duration_cast<std::chrono::seconds>(
lastWokenUp + std::chrono::seconds(settings.pollInterval) - before).count()); lastWokenUp + std::chrono::seconds(settings.pollInterval) - before).count());
} else lastWokenUp = steady_time_point::min(); } else lastWokenUp = steady_time_point::min();
if (useTimeout) 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 /* Use select() to wait for the input side of any logger pipe to
become `available'. Note that `available' (i.e., non-blocking) become `available'. Note that `available' (i.e., non-blocking)
includes EOF. */ includes EOF. */
fd_set fds; std::vector<struct pollfd> pollStatus;
FD_ZERO(&fds); std::map <int, int> fdToPollStatus;
int fdMax = 0;
for (auto & i : children) { for (auto & i : children) {
for (auto & j : i.fds) { for (auto & j : i.fds) {
if (j >= FD_SETSIZE) pollStatus.push_back((struct pollfd) { .fd = j, .events = POLLIN });
throw Error("reached FD_SETSIZE limit"); fdToPollStatus[j] = pollStatus.size() - 1;
FD_SET(j, &fds);
if (j >= fdMax) fdMax = j + 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; if (errno == EINTR) return;
throw SysError("waiting for input"); throw SysError("waiting for input");
} }
@ -4863,7 +4860,7 @@ void Worker::waitForInput()
set<int> fds2(j->fds); set<int> fds2(j->fds);
std::vector<unsigned char> buffer(4096); std::vector<unsigned char> buffer(4096);
for (auto & k : fds2) { 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()); ssize_t rd = read(k, buffer.data(), buffer.size());
// FIXME: is there a cleaner way to handle pt close // FIXME: is there a cleaner way to handle pt close
// than EIO? Is this even standard? // than EIO? Is this even standard?