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Make s_generation_count a std::atomic

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This should improve safety and satisfy tsan
This commit is contained in:
ridiculousfish 2017-03-26 13:44:27 -07:00
parent 44b3554a11
commit dec0f7aa84
1 changed files with 14 additions and 10 deletions
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24
src/reader.cpp
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@ -36,6 +36,7 @@
#include <wctype.h> #include <wctype.h>
#include <algorithm> #include <algorithm>
#include <atomic>
#include <csignal> #include <csignal>
#include <functional> #include <functional>
#include <memory> #include <memory>
@ -126,16 +127,18 @@
#define SEARCH_FORWARD 1 #define SEARCH_FORWARD 1
/// Any time the contents of a buffer changes, we update the generation count. This allows for our /// Any time the contents of a buffer changes, we update the generation count. This allows for our
/// background highlighting thread to notice it and skip doing work that it would otherwise have to /// background threads to notice it and skip doing work that they would otherwise have to do.
/// do. This variable should really be of some kind of interlocked or atomic type that guarantees static std::atomic<unsigned int> s_generation_count;
/// we're not reading stale cache values. With C++11 we should use atomics, but until then volatile
/// should work as well, at least on x86.
static volatile unsigned int s_generation_count;
/// This pthreads generation count is set when an autosuggestion background thread starts up, so it /// This pthreads generation count is set when an autosuggestion background thread starts up, so it
/// can easily check if the work it is doing is no longer useful. /// can easily check if the work it is doing is no longer useful.
static pthread_key_t generation_count_key; static pthread_key_t generation_count_key;
/// Helper to get the generation count
static unsigned int read_generation_count() {
return s_generation_count.load(std::memory_order_relaxed);
}
static void set_command_line_and_position(editable_line_t *el, const wcstring &new_str, size_t pos); static void set_command_line_and_position(editable_line_t *el, const wcstring &new_str, size_t pos);
void editable_line_t::insert_string(const wcstring &str, size_t start, size_t len) { void editable_line_t::insert_string(const wcstring &str, size_t start, size_t len) {
@ -658,7 +661,8 @@ int reader_reading_interrupted() {
bool reader_thread_job_is_stale() { bool reader_thread_job_is_stale() {
ASSERT_IS_BACKGROUND_THREAD(); ASSERT_IS_BACKGROUND_THREAD();
return (void *)(uintptr_t)s_generation_count != pthread_getspecific(generation_count_key); void *current_count = (void *)(uintptr_t)read_generation_count();
return current_count != pthread_getspecific(generation_count_key);
} }
void reader_write_title(const wcstring &cmd, bool reset_cursor_position) { void reader_write_title(const wcstring &cmd, bool reset_cursor_position) {
@ -1118,7 +1122,7 @@ struct autosuggestion_result_t {
// on a background thread) to determine the autosuggestion // on a background thread) to determine the autosuggestion
static std::function<autosuggestion_result_t(void)> get_autosuggestion_performer( static std::function<autosuggestion_result_t(void)> get_autosuggestion_performer(
const wcstring &search_string, size_t cursor_pos, history_t *history) { const wcstring &search_string, size_t cursor_pos, history_t *history) {
const unsigned int generation_count = s_generation_count; const unsigned int generation_count = read_generation_count();
const wcstring working_directory(env_get_pwd_slash()); const wcstring working_directory(env_get_pwd_slash());
env_vars_snapshot_t vars(env_vars_snapshot_t::highlighting_keys); env_vars_snapshot_t vars(env_vars_snapshot_t::highlighting_keys);
// TODO: suspicious use of 'history' here // TODO: suspicious use of 'history' here
@ -1129,7 +1133,7 @@ static std::function<autosuggestion_result_t(void)> get_autosuggestion_performer
const autosuggestion_result_t nothing = {}; const autosuggestion_result_t nothing = {};
// If the main thread has moved on, skip all the work. // If the main thread has moved on, skip all the work.
if (generation_count != s_generation_count) { if (generation_count != read_generation_count()) {
return nothing; return nothing;
} }
@ -2103,10 +2107,10 @@ static std::function<highlight_result_t(void)> get_highlight_performer(const wcs
long match_highlight_pos, long match_highlight_pos,
bool no_io) { bool no_io) {
env_vars_snapshot_t vars(env_vars_snapshot_t::highlighting_keys); env_vars_snapshot_t vars(env_vars_snapshot_t::highlighting_keys);
unsigned int generation_count = s_generation_count; unsigned int generation_count = read_generation_count();
highlight_function_t highlight_func = no_io ? highlight_shell_no_io : data->highlight_function; highlight_function_t highlight_func = no_io ? highlight_shell_no_io : data->highlight_function;
return [=]() -> highlight_result_t { return [=]() -> highlight_result_t {
if (generation_count != s_generation_count) { if (generation_count != read_generation_count()) {
// The gen count has changed, so don't do anything. // The gen count has changed, so don't do anything.
return {}; return {};
} }