60 lines
1.8 KiB
Go
60 lines
1.8 KiB
Go
// Copyright IBM Corp. 2020, 2026
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// SPDX-License-Identifier: BUSL-1.1
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package password
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import (
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"context"
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"sync"
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"github.com/hashicorp/boundary/internal/errors"
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"github.com/hashicorp/go-secure-stdlib/permitpool"
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)
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// resizablePermitPool is a permit pool that can be resized at runtime.
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type resizablePermitPool struct {
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pool *permitpool.Pool
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// lock is used to synchronize access to the permit pool
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// This is an RWMutex to allow an unlimited number of readers
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// and a single writer, since allowing a single reader or writer
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// would effectively make the pool useless.
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lock *sync.RWMutex
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}
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// newResizablePermitPool creates a new resizable permit pool with n permits.
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func newResizablePermitPool(n int) *resizablePermitPool {
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return &resizablePermitPool{
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pool: permitpool.New(n),
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lock: &sync.RWMutex{},
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}
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}
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// SetPermit sets the number of permits available in the pool.
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func (r *resizablePermitPool) SetPermits(n int) error {
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const op = "resizablePermitPool.SetPermits"
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if n <= 0 {
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return errors.New(context.Background(), errors.InvalidParameter, op, "n must be greater than 0")
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}
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// Taking a write lock ensures there are no currently acquired permits
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r.lock.Lock()
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defer r.lock.Unlock()
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r.pool = permitpool.New(n)
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return nil
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}
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// Do executes the provided function with a permit acquired from the pool.
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// If the context is canceled while waiting to acquire a permit, an error is returned.
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func (r *resizablePermitPool) Do(ctx context.Context, fn func()) error {
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const op = "resizablePermitPool.Do"
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// We need to ensure both the Acquire and Release happen while the read lock is held,
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// so that the pool cannot be resized in between.
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r.lock.RLock()
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defer r.lock.RUnlock()
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if err := r.pool.Acquire(ctx); err != nil {
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return errors.Wrap(ctx, err, op, errors.WithMsg("failed to acquire permit"))
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}
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defer r.pool.Release()
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fn()
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return nil
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}
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