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add global connection pool for mysql
Signed-off-by: Rob Pickerill <r.pickerill@gmail.com>
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package util | ||
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//nolint:depguard // sync/atomic | ||
import ( | ||
"fmt" | ||
"sync" | ||
"sync/atomic" | ||
) | ||
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// refCountedValue manages a reference-counted value with a cleanup function. | ||
type refCountedValue[V any] struct { | ||
value V | ||
refCount atomic.Int64 | ||
closeFunc func(V) error // Cleanup function to call when count reaches zero | ||
} | ||
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// Add increments the reference count. | ||
func (r *refCountedValue[V]) Add() { | ||
r.refCount.Add(1) | ||
} | ||
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// Remove decrements the reference count and invokes closeFunc if the count | ||
// reaches zero. | ||
func (r *refCountedValue[V]) Remove() error { | ||
if r.refCount.Add(-1) == 0 { | ||
return r.closeFunc(r.value) | ||
} | ||
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return nil | ||
} | ||
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// Value returns the underlying value. | ||
func (r *refCountedValue[V]) Value() V { | ||
return r.value | ||
} | ||
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// RefMap manages reference-counted items in a concurrent-safe map. | ||
type RefMap[K comparable, V any] struct { | ||
data map[K]*refCountedValue[V] | ||
mu sync.RWMutex | ||
} | ||
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// NewRefMap initializes a new RefMap. A RefMap is an atomic reference-counted | ||
// concurrent hashmap. The general usage pattern is to Store a value with a | ||
// close function, once the value is contained within the RefMap, it can be | ||
// accessed via the Load method. The AddRef method signals ownership of the | ||
// value and increments the reference count. The RemoveRef method decrements | ||
// the reference count. When the reference count reaches zero, the close | ||
// function is called and the value is removed from the map. | ||
func NewRefMap[K comparable, V any]() *RefMap[K, V] { | ||
return &RefMap[K, V]{ | ||
data: make(map[K]*refCountedValue[V]), | ||
} | ||
} | ||
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// Store adds a new item with an initial reference count of 1 and a close | ||
// function. | ||
func (r *RefMap[K, V]) Store(key K, value V, closeFunc func(V) error) error { | ||
r.mu.Lock() | ||
defer r.mu.Unlock() | ||
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if _, exists := r.data[key]; exists { | ||
return fmt.Errorf("key already exists: %v", key) | ||
} | ||
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r.data[key] = &refCountedValue[V]{value: value, refCount: atomic.Int64{}, closeFunc: closeFunc} | ||
r.data[key].Add() // Set initial reference count to 1 | ||
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return nil | ||
} | ||
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// Load retrieves a value by key without modifying the reference count, | ||
// returning the value and a boolean indicating if it was found. The reference | ||
// count not being modified means that a check for the existence of a key | ||
// can be performed with signalling ownership of the value. If the value is used | ||
// after this method, it is recommended to call AddRef to increment the | ||
// reference | ||
func (r *RefMap[K, V]) Load(key K) (V, bool) { | ||
r.mu.RLock() | ||
defer r.mu.RUnlock() | ||
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if refValue, found := r.data[key]; found { | ||
return refValue.Value(), true | ||
} | ||
var zero V | ||
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return zero, false | ||
} | ||
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// AddRef increments the reference count for a key if it exists. Ensure | ||
// to call RemoveRef when done with the value to prevent memory leaks. | ||
func (r *RefMap[K, V]) AddRef(key K) error { | ||
r.mu.RLock() | ||
defer r.mu.RUnlock() | ||
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refValue, found := r.data[key] | ||
if !found { | ||
return fmt.Errorf("key not found: %v", key) | ||
} | ||
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refValue.Add() | ||
return nil | ||
} | ||
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// RemoveRef decrements the reference count and deletes the entry if count | ||
// reaches zero. | ||
func (r *RefMap[K, V]) RemoveRef(key K) error { | ||
r.mu.Lock() | ||
defer r.mu.Unlock() | ||
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refValue, found := r.data[key] | ||
if !found { | ||
return fmt.Errorf("key not found: %v", key) | ||
} | ||
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err := refValue.Remove() | ||
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if refValue.refCount.Load() == 0 { | ||
delete(r.data, key) | ||
} | ||
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return err // returns the error from closeFunc | ||
} |
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