bryancall commented on code in PR #11271:
URL: https://github.com/apache/trafficserver/pull/11271#discussion_r1575406770
##########
plugins/experimental/rate_limit/limiter.h:
##########
@@ -24,16 +24,129 @@
#include <string>
#include <climits>
#include <mutex>
+#include <thread>
#include "tscore/ink_config.h"
#include "ts/ts.h"
#include <yaml-cpp/yaml.h>
#include "utilities.h"
-constexpr auto QUEUE_DELAY_TIME = std::chrono::milliseconds{300}; // Examine
the queue every 300ms
-using QueueTime =
std::chrono::time_point<std::chrono::system_clock>;
+constexpr auto BUCKET_REFILL_INTERVAL = std::chrono::milliseconds{25}; //
Increase rate limit buckets every 25ms
+constexpr auto QUEUE_DELAY_TIME = std::chrono::milliseconds{300}; //
Examine the queue every 300ms
+using QueueTime =
std::chrono::time_point<std::chrono::system_clock>;
-enum { RATE_LIMITER_TYPE_SNI = 0, RATE_LIMITER_TYPE_REMAP,
RATE_LIMITER_TYPE_MAX };
+int bucket_refill_cont(TSCont cont, TSEvent event, void *edata);
+class BucketManager
+{
+ using self_type = BucketManager;
+
+public:
+ class RateBucket
+ {
+ using self_type = RateBucket;
+
+ public:
+ RateBucket(uint32_t max) : _count(0), _max(max) {}
+ ~RateBucket() = default;
+
+ RateBucket(self_type &&) = delete;
+ self_type &operator=(const self_type &) = delete;
+ self_type &operator=(self_type &&) = delete;
+
+ uint32_t
+ count() const
+ {
+ return _count.load(std::memory_order_acquire);
+ }
+
+ bool
+ consume()
+ {
+ uint32_t val = _count.load(std::memory_order_acquire);
+
+ while (val > 0) {
+ if (_count.compare_exchange_weak(val, val - 1,
std::memory_order_release, std::memory_order_acquire)) {
+ break;
+ }
+ }
+ TSReleaseAssert(val <= _max);
+
+ return val > 0;
+ }
+
+ // This should only be called from the manager, as such no locking is
needed
+ protected:
+ void
+ refill()
+ {
+ static const uint32_t amount = _max / (1000 /
BUCKET_REFILL_INTERVAL.count());
+ uint32_t old = _count.load(std::memory_order_acquire);
+ uint32_t nval;
+
+ do {
+ nval = old + amount;
+ } while (!_count.compare_exchange_weak(old, std::min(nval, _max),
std::memory_order_release, std::memory_order_acquire));
+ }
+
+ private:
+ friend class BucketManager;
+
+ std::atomic<uint32_t> _count;
+ uint32_t _max;
+
+ }; // End class RateBucket
+
+ BucketManager() = default;
+ ~BucketManager()
+ {
+ if (_running) {
+ _running = false;
+ _thread.join(); // Wait for the thread to finish
+ }
+ }
+
+ BucketManager(self_type &&) = delete;
+ self_type &operator=(const self_type &) = delete;
+ self_type &operator=(self_type &&) = delete;
+
+ void refill_thread();
+
+ std::shared_ptr<RateBucket>
+ add(uint32_t max)
+ {
+ auto bucket = std::make_shared<RateBucket>(max);
+ std::lock_guard<std::mutex> lock(_mutex);
+
+ if (!_running) {
+ _running = true;
+ _thread = std::thread(&BucketManager::refill_thread, this);
+ }
+
+ _buckets.push_back(bucket);
+
+ return bucket;
+ }
+
+ void
+ remove(std::shared_ptr<RateBucket> bucket)
+ {
+ std::lock_guard<std::mutex> lock(_mutex);
+ auto it = std::find(_buckets.begin(), _buckets.end(), bucket);
+
+ if (it != _buckets.end()) {
+ _buckets.erase(it);
+ }
+ }
+
+private:
+ std::vector<std::shared_ptr<RateBucket>> _buckets;
+ std::mutex _mutex; // Protect the bucket list
+ bool _running = false; // Is the Bucket manager thread running already ?
+ std::thread _thread; // The thread refilling the buckets
+
+}; // End class BucketManager
+
+extern BucketManager gBucketMngr;
// order must align with the above
static const char *types[] = {
Review Comment:
Seeing this on the CI builds:
```
../plugins/experimental/rate_limit/limiter.h:168:20: error: 'suffixes'
defined but not used [-Werror=unused-variable]
168 | static const char *suffixes[] = {
| ^~~~~~~~
../plugins/experimental/rate_limit/limiter.h:152:20: error: 'types' defined
but not used [-Werror=unused-variable]
152 | static const char *types[] = {
| ^~~~~
cc1plus: note: unrecognized command-line option '-Wno-vla-extension' may
have been intended to silence earlier diagnostics
```
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