forked from TrueCloudLab/frostfs-node
[#1248] node: Do not update cache twice
Do not request morph values on morph cache misses concurrently. Signed-off-by: Pavel Karpy <p.karpy@yadro.com>
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commit
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2 changed files with 56 additions and 9 deletions
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@ -70,6 +70,7 @@ Changelog for FrostFS Node
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- Non-alphabet nodes do not try to handle alphabet events (#181)
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- Failing SN and IR transactions because of incorrect scopes (#2230, #2263)
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- Global scope used for some transactions (#2230, #2263)
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- Concurrent morph cache misses (#30)
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### Removed
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### Updated
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@ -24,9 +24,19 @@ type valueWithTime[V any] struct {
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e error
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}
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// valueInProgress is a struct that contains
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// values that are being fetched/updated.
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type valueInProgress[V any] struct {
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m sync.RWMutex
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v V
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e error
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}
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// entity that provides TTL cache interface.
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type ttlNetCache[K comparable, V any] struct {
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ttl time.Duration
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m sync.RWMutex // protects progMap
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progMap map[K]*valueInProgress[V] // contains fetch-in-progress keys
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ttl time.Duration
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sz int
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@ -41,32 +51,68 @@ func newNetworkTTLCache[K comparable, V any](sz int, ttl time.Duration, netRdr n
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fatalOnErr(err)
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return &ttlNetCache[K, V]{
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ttl: ttl,
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sz: sz,
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cache: cache,
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netRdr: netRdr,
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ttl: ttl,
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sz: sz,
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cache: cache,
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netRdr: netRdr,
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progMap: make(map[K]*valueInProgress[V]),
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}
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}
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func waitForUpdate[V any](vip *valueInProgress[V]) (V, error) {
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vip.m.RLock()
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defer vip.m.RUnlock()
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return vip.v, vip.e
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}
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// reads value by the key.
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//
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// updates the value from the network on cache miss or by TTL.
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//
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// returned value should not be modified.
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func (c *ttlNetCache[K, V]) get(key K) (V, error) {
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val, ok := c.cache.Peek(key)
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valWithTime, ok := c.cache.Peek(key)
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if ok {
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if time.Since(val.t) < c.ttl {
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return val.v, val.e
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if time.Since(valWithTime.t) < c.ttl {
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return valWithTime.v, valWithTime.e
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}
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c.cache.Remove(key)
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}
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v, err := c.netRdr(key)
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c.m.RLock()
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valInProg, ok := c.progMap[key]
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c.m.RUnlock()
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if ok {
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return waitForUpdate(valInProg)
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}
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c.m.Lock()
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valInProg, ok = c.progMap[key]
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if ok {
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c.m.Unlock()
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return waitForUpdate(valInProg)
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}
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valInProg = &valueInProgress[V]{}
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valInProg.m.Lock()
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c.progMap[key] = valInProg
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c.m.Unlock()
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v, err := c.netRdr(key)
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c.set(key, v, err)
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valInProg.v = v
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valInProg.e = err
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valInProg.m.Unlock()
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c.m.Lock()
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delete(c.progMap, key)
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c.m.Unlock()
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return v, err
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}
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