2023-10-20 10:16:19 +03:00
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// Many build systems attempt to invoke as many linker processes as there
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// are cores, based on the assumption that the linker is single-threaded.
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// However, since mold is multi-threaded, such build systems' behavior is
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// not beneficial and just increases the overall peak memory usage.
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// On machines with limited memory, this could lead to an out-of-memory
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// error.
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//
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// This file implements a feature that limits the number of concurrent
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// mold processes to just 1 for each user. It is intended to be used as
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// `MOLD_JOBS=1 ninja` or `MOLD_JOBS=1 make -j$(nproc)`.
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2023-03-17 09:32:12 +03:00
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#include "mold.h"
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#ifndef _WIN32
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# include <fcntl.h>
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# include <pwd.h>
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# include <sys/stat.h>
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# include <sys/types.h>
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# include <unistd.h>
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#endif
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namespace mold::elf {
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template <typename E>
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void acquire_global_lock(Context<E> &ctx) {
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#ifndef _WIN32
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char *jobs = getenv("MOLD_JOBS");
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if (!jobs || std::string(jobs) != "1")
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return;
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char *home = getenv("HOME");
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if (!home)
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home = getpwuid(getuid())->pw_dir;
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std::string path = std::string(home) + "/.mold-lock";
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int fd = open(path.c_str(), O_WRONLY | O_CREAT | O_CLOEXEC, 0600);
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if (fd == -1)
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return;
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if (lockf(fd, F_LOCK, 0) == -1)
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return;
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ctx.global_lock_fd = fd;
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#endif
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}
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template <typename E>
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void release_global_lock(Context<E> &ctx) {
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#ifndef _WIN32
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if (ctx.global_lock_fd)
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close(*ctx.global_lock_fd);
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#endif
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}
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using E = MOLD_TARGET;
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template void acquire_global_lock(Context<E> &);
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template void release_global_lock(Context<E> &);
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} // namespace mold::elf
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