milvus-io--milvus
wehub-resource-sync
498b235461
Build and test / Build and test AMD64 Ubuntu 22.04 (push) Failing after 0s
Publish Builder / amazonlinux2023 (push) Failing after 1s
Build and test / UT for Go (push) Has been skipped
Publish KRTE Images / KRTE (push) Failing after 1s
Build and test / Integration Test (push) Has been skipped
Build and test / Upload Code Coverage (push) Has been skipped
Publish Builder / rockylinux9 (push) Failing after 1s
Publish Builder / ubuntu22.04 (push) Failing after 0s
Publish Builder / ubuntu24.04 (push) Failing after 0s
Publish Gpu Builder / publish-gpu-builder (push) Failing after 1s
Publish Test Images / PyTest (push) Failing after 0s
Build and test / UT for Cpp (push) Has been cancelled
99 行
2.5 KiB
Go
99 行
2.5 KiB
Go
package syncutil
|
|
|
|
import (
|
|
"context"
|
|
"sync"
|
|
)
|
|
|
|
// Semaphore is a counting semaphore with dynamically adjustable capacity.
|
|
//
|
|
// It supports context-aware Acquire (can be canceled/timed out) and non-blocking
|
|
// TryAcquire. The capacity can be changed at runtime via SetCapacity; waiters are
|
|
// woken up when capacity increases.
|
|
type Semaphore struct {
|
|
mu sync.Mutex
|
|
cond *ContextCond
|
|
|
|
capacity int // maximum number of concurrent holders
|
|
current int // number of currently held tokens
|
|
}
|
|
|
|
// NewSemaphore creates a semaphore with the given initial capacity.
|
|
// Panics if capacity <= 0.
|
|
func NewSemaphore(capacity int) *Semaphore {
|
|
if capacity <= 0 {
|
|
panic("syncutil: semaphore capacity must be positive")
|
|
}
|
|
s := &Semaphore{
|
|
capacity: capacity,
|
|
}
|
|
s.cond = NewContextCond(&s.mu)
|
|
return s
|
|
}
|
|
|
|
// Acquire blocks until a token is available or ctx is canceled.
|
|
// Returns nil on success, or the context error on cancellation/timeout.
|
|
func (s *Semaphore) Acquire(ctx context.Context) error {
|
|
s.mu.Lock()
|
|
for s.current >= s.capacity {
|
|
if err := s.cond.Wait(ctx); err != nil {
|
|
// cond.Wait does NOT re-acquire the lock on error.
|
|
return err
|
|
}
|
|
}
|
|
s.current++
|
|
s.mu.Unlock()
|
|
return nil
|
|
}
|
|
|
|
// TryAcquire attempts to acquire a token without blocking.
|
|
// Returns true if a token was acquired, false if the semaphore is full.
|
|
func (s *Semaphore) TryAcquire() bool {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
if s.current >= s.capacity {
|
|
return false
|
|
}
|
|
s.current++
|
|
return true
|
|
}
|
|
|
|
// Release returns a token to the semaphore, waking one waiter if any.
|
|
func (s *Semaphore) Release() {
|
|
s.cond.LockAndBroadcast()
|
|
if s.current <= 0 {
|
|
s.mu.Unlock()
|
|
panic("syncutil: semaphore release without acquire")
|
|
}
|
|
s.current--
|
|
s.mu.Unlock()
|
|
}
|
|
|
|
// SetCapacity dynamically adjusts the semaphore capacity.
|
|
// If the new capacity is larger, blocked Acquire calls may proceed.
|
|
// If smaller, no tokens are revoked — the semaphore simply won't grant new
|
|
// tokens until current holders release enough to drop below the new capacity.
|
|
// Panics if capacity <= 0.
|
|
func (s *Semaphore) SetCapacity(capacity int) {
|
|
if capacity <= 0 {
|
|
panic("syncutil: semaphore capacity must be positive")
|
|
}
|
|
s.cond.LockAndBroadcast()
|
|
s.capacity = capacity
|
|
s.mu.Unlock()
|
|
}
|
|
|
|
// Cap returns the current capacity.
|
|
func (s *Semaphore) Cap() int {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
return s.capacity
|
|
}
|
|
|
|
// Current returns the number of currently held tokens.
|
|
func (s *Semaphore) Current() int {
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
return s.current
|
|
}
|