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seaweedfs/weed/wdclient/resource_pool/multi_resource_pool.go
Chris Lu 1444e9d275 migrated multi host connection pool from godropbox package
removing unneeded dependencies, which involved etcd versions.
2021-03-06 14:26:27 -08:00

201 lines
4.4 KiB
Go

package resource_pool
import (
"fmt"
"sync"
"errors"
)
// A resource pool implementation that manages multiple resource location
// entries. The handles to each resource location entry acts independently.
// For example "tcp localhost:11211" could act as memcache
// shard 0 and "tcp localhost:11212" could act as memcache shard 1.
type multiResourcePool struct {
options Options
createPool func(Options) ResourcePool
rwMutex sync.RWMutex
isLameDuck bool // guarded by rwMutex
// NOTE: the locationPools is guarded by rwMutex, but the pool entries
// are not.
locationPools map[string]ResourcePool
}
// This returns a MultiResourcePool, which manages multiple
// resource location entries. The handles to each resource location
// entry acts independently.
//
// When createPool is nil, NewSimpleResourcePool is used as default.
func NewMultiResourcePool(
options Options,
createPool func(Options) ResourcePool) ResourcePool {
if createPool == nil {
createPool = NewSimpleResourcePool
}
return &multiResourcePool{
options: options,
createPool: createPool,
rwMutex: sync.RWMutex{},
isLameDuck: false,
locationPools: make(map[string]ResourcePool),
}
}
// See ResourcePool for documentation.
func (p *multiResourcePool) NumActive() int32 {
total := int32(0)
p.rwMutex.RLock()
defer p.rwMutex.RUnlock()
for _, pool := range p.locationPools {
total += pool.NumActive()
}
return total
}
// See ResourcePool for documentation.
func (p *multiResourcePool) ActiveHighWaterMark() int32 {
high := int32(0)
p.rwMutex.RLock()
defer p.rwMutex.RUnlock()
for _, pool := range p.locationPools {
val := pool.ActiveHighWaterMark()
if val > high {
high = val
}
}
return high
}
// See ResourcePool for documentation.
func (p *multiResourcePool) NumIdle() int {
total := 0
p.rwMutex.RLock()
defer p.rwMutex.RUnlock()
for _, pool := range p.locationPools {
total += pool.NumIdle()
}
return total
}
// See ResourcePool for documentation.
func (p *multiResourcePool) Register(resourceLocation string) error {
if resourceLocation == "" {
return errors.New("Registering invalid resource location")
}
p.rwMutex.Lock()
defer p.rwMutex.Unlock()
if p.isLameDuck {
return fmt.Errorf(
"Cannot register %s to lame duck resource pool",
resourceLocation)
}
if _, inMap := p.locationPools[resourceLocation]; inMap {
return nil
}
pool := p.createPool(p.options)
if err := pool.Register(resourceLocation); err != nil {
return err
}
p.locationPools[resourceLocation] = pool
return nil
}
// See ResourcePool for documentation.
func (p *multiResourcePool) Unregister(resourceLocation string) error {
p.rwMutex.Lock()
defer p.rwMutex.Unlock()
if pool, inMap := p.locationPools[resourceLocation]; inMap {
_ = pool.Unregister("")
pool.EnterLameDuckMode()
delete(p.locationPools, resourceLocation)
}
return nil
}
func (p *multiResourcePool) ListRegistered() []string {
p.rwMutex.RLock()
defer p.rwMutex.RUnlock()
result := make([]string, 0, len(p.locationPools))
for key, _ := range p.locationPools {
result = append(result, key)
}
return result
}
// See ResourcePool for documentation.
func (p *multiResourcePool) Get(
resourceLocation string) (ManagedHandle, error) {
pool := p.getPool(resourceLocation)
if pool == nil {
return nil, fmt.Errorf(
"%s is not registered in the resource pool",
resourceLocation)
}
return pool.Get(resourceLocation)
}
// See ResourcePool for documentation.
func (p *multiResourcePool) Release(handle ManagedHandle) error {
pool := p.getPool(handle.ResourceLocation())
if pool == nil {
return errors.New(
"Resource pool cannot take control of a handle owned " +
"by another resource pool")
}
return pool.Release(handle)
}
// See ResourcePool for documentation.
func (p *multiResourcePool) Discard(handle ManagedHandle) error {
pool := p.getPool(handle.ResourceLocation())
if pool == nil {
return errors.New(
"Resource pool cannot take control of a handle owned " +
"by another resource pool")
}
return pool.Discard(handle)
}
// See ResourcePool for documentation.
func (p *multiResourcePool) EnterLameDuckMode() {
p.rwMutex.Lock()
defer p.rwMutex.Unlock()
p.isLameDuck = true
for _, pool := range p.locationPools {
pool.EnterLameDuckMode()
}
}
func (p *multiResourcePool) getPool(resourceLocation string) ResourcePool {
p.rwMutex.RLock()
defer p.rwMutex.RUnlock()
if pool, inMap := p.locationPools[resourceLocation]; inMap {
return pool
}
return nil
}