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Hopeful fix to avoid forking for certain builtins like echo when they have an input redirection only

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This commit is contained in:
ridiculousfish 2013-02-22 13:20:27 -08:00
parent 3c8c8a7559
commit 9f8fe3d5e3
3 changed files with 26 additions and 14 deletions
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20
exec.cpp
View file

@ -1159,23 +1159,25 @@ void exec(parser_t &parser, job_t *j)
performance quite a bit in complex completion code.
*/
const shared_ptr<io_data_t> &io = io_chain_get(j->io, 1);
bool buffer_stdout = io && io->io_mode == IO_BUFFER;
const shared_ptr<io_data_t> &stdout_io = io_chain_get(j->io, STDOUT_FILENO);
const shared_ptr<io_data_t> &stderr_io = io_chain_get(j->io, STDERR_FILENO);
const bool buffer_stdout = stdout_io && stdout_io->io_mode == IO_BUFFER;
if ((get_stderr_buffer().empty()) &&
(!p->next) &&
(! get_stdout_buffer().empty()) &&
(buffer_stdout))
{
CAST_INIT(io_buffer_t *, io_buffer, io.get());
CAST_INIT(io_buffer_t *, io_buffer, stdout_io.get());
const std::string res = wcs2string(get_stdout_buffer());
io_buffer->out_buffer_append(res.c_str(), res.size());
skip_fork = true;
}
if (! skip_fork && j->io.empty())
/* PCA for some reason, fish forks a lot, even for basic builtins like echo just to write out their buffers. I'm certain a lot of this is unnecessary, but I am not sure exactly when. If j->io is NULL, then it means there's no pipes or anything, so we can certainly just write out our data. Beyond that, we may be able to do the same if io_get returns 0 for STDOUT_FILENO and STDERR_FILENO.
*/
if (! skip_fork && stdout_io.get() == NULL && stderr_io.get() == NULL)
{
/* PCA for some reason, fish forks a lot, even for basic builtins like echo just to write out their buffers. I'm certain a lot of this is unnecessary, but I am not sure exactly when. If j->io is NULL, then it means there's no pipes or anything, so we can certainly just write out our data. Beyond that, we may be able to do the same if io_get returns 0 for STDOUT_FILENO and STDERR_FILENO. */
if (g_log_forks)
{
printf("fork #-: Skipping fork for internal builtin for '%ls'\n", p->argv0());
@ -1194,12 +1196,16 @@ void exec(parser_t &parser, job_t *j)
for (io_chain_t::iterator iter = j->io.begin(); iter != j->io.end(); ++iter)
{
const shared_ptr<io_data_t> &tmp_io = *iter;
if (tmp_io->io_mode == IO_FILE && strcmp(static_cast<const io_file_t *>(tmp_io.get())->filename_cstr, "/dev/null") != 0)
if (tmp_io->io_mode == IO_FILE)
{
const io_file_t *tmp_file_io = static_cast<const io_file_t *>(tmp_io.get());
if (strcmp(tmp_file_io->filename_cstr, "/dev/null"))
{
skip_fork = false;
break;
}
}
}
if (skip_fork)
@ -1235,7 +1241,7 @@ void exec(parser_t &parser, job_t *j)
if (g_log_forks)
{
printf("fork #%d: Executing fork for internal builtin for '%ls'\n", g_fork_count, p->argv0());
io_print(io_chain_t(io));
io_print(j->io);
}
pid = execute_fork(false);
if (pid == 0)

9
io.cpp
View file

@ -209,7 +209,7 @@ void io_chain_t::push_back(const shared_ptr<io_data_t> &element)
{
// Ensure we never push back NULL
assert(element.get() != NULL);
std::vector<shared_ptr<io_data_t> >:: push_back(element);
std::vector<shared_ptr<io_data_t> >::push_back(element);
}
void io_remove(io_chain_t &list, const shared_ptr<const io_data_t> &element)
@ -229,9 +229,16 @@ void io_print(const io_chain_t &chain)
for (size_t i=0; i < chain.size(); i++)
{
const shared_ptr<const io_data_t> &io = chain.at(i);
if (io.get() == NULL)
{
fprintf(stderr, "\t(null)\n");
}
else
{
fprintf(stderr, "\t%lu: fd:%d, ", (unsigned long)i, io->fd);
io->print();
}
}
}
/* Return the last IO for the given fd */

1
io.h
View file

@ -184,7 +184,6 @@ public:
shared_ptr<const io_data_t> get_io_for_fd(int fd) const;
shared_ptr<io_data_t> get_io_for_fd(int fd);
};
/**