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Make more threading improvements

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- ASAN memory morgue is now lockless
- Make C11 atomics header more portable
- Rewrote pthread keys support to be lockless
- Simplify Python's unicode table unpacking code
- Make crash report write(2) closer to being atomic
- Make it possible to strace/ftrace a single thread
- ASAN now checks nul-terminated strings fast and properly
- Windows fork() now restores TLS memory of calling thread
This commit is contained in:
Justine Tunney 2022-11-01 22:36:03 -07:00
parent d7b88734cd
commit e522aa3a07
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GPG key ID: BE714B4575D6E328
189 changed files with 1363 additions and 1217 deletions
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24
net/http/tokenbucket.c
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@ -20,7 +20,7 @@
#include "net/http/tokenbucket.h"
/**
* Atomically increments all signed bytes in array without overflow.
* Atomically increments all signed bytes in array, without overflowing.
*
* Under the token bucket model, operations are denied by default unless
* tokens exist to allow them. This function must be called periodically
@ -39,7 +39,7 @@ void ReplenishTokens(atomic_uint_fast64_t *w, size_t n) {
uint64_t a = atomic_load_explicit(w + i, memory_order_relaxed);
if (a == 0x7f7f7f7f7f7f7f7f) continue;
uint64_t b = 0x8080808080808080;
uint64_t c = a ^ 0x7f7f7f7f7f7f7f7f;
uint64_t c = 0x7f7f7f7f7f7f7f7f ^ a;
uint64_t d = ((c >> 1 | b) - c & b ^ b) >> 7;
atomic_fetch_add_explicit(w + i, d, memory_order_relaxed);
}
@ -48,13 +48,13 @@ void ReplenishTokens(atomic_uint_fast64_t *w, size_t n) {
/**
* Atomically decrements signed byte index if it's positive.
*
* Multiple threads may call this method to determine if sufficient
* Multiple threads are able to call this method, to determine if enough
* tokens exist to perform an operation. Return values greater than zero
* mean a token was atomically acquired. Values less than or equal zero
* mean a token was atomically acquired. Values less than, or equal zero
* means the bucket is empty. There must exist `1 << c` signed bytes (or
* buckets) in the `b` array.
*
* Since this design uses signed bytes, the returned number may be used
* Since this design uses signed bytes, your returned number may be used
* to control how much burstiness is allowed. For example:
*
* int t = AcquireToken(tok.b, ip, 22);
@ -64,12 +64,12 @@ void ReplenishTokens(atomic_uint_fast64_t *w, size_t n) {
* return;
* }
*
* May be used to send a rejection to clients who've exceeded their
* tokens whereas clients who've grossly exceeded their tokens will
* simply be dropped.
* Could be used to send rejections to clients that exceed their tokens,
* whereas clients who've grossly exceeded their tokens, could simply be
* dropped.
*
* @param w is array of token buckets
* @param n is ipv4 address
* @param b is array of token buckets
* @param x is ipv4 address
* @param c is cidr
*/
int AcquireToken(atomic_schar *b, uint32_t x, int c) {
@ -82,8 +82,8 @@ int AcquireToken(atomic_schar *b, uint32_t x, int c) {
/**
* Returns current number of tokens in bucket.
*
* @param w is array of token buckets
* @param n is ipv4 address
* @param b is array of token buckets
* @param x is ipv4 address
* @param c is cidr
*/
int CountTokens(atomic_schar *b, uint32_t x, int c) {