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e67d45caa1
This change allows functions to be "idled" or scaled to zero replicas and then be invoked later on. There is a penalty to scaling up - the API gateway proxy will block until the function is ready. A cache is included to off-set the calls to upstream API to check on readiness along with unit tests. Testing via scaling to zero replicas and then invoking function. On Swarm I observed 3 seconds on an Intel Nuc i5 for scaling back from zero replicas. Signed-off-by: Alex Ellis (VMware) <alexellis2@gmail.com>
60 lines
1.4 KiB
Go
60 lines
1.4 KiB
Go
// Copyright (c) OpenFaaS Project. All rights reserved.
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// Licensed under the MIT license. See LICENSE file in the project root for full license information.
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package handlers
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import (
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"sync"
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"time"
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)
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// FunctionMeta holds the last refresh and any other
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// meta-data needed for caching.
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type FunctionMeta struct {
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LastRefresh time.Time
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Replicas uint64
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}
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// Expired find out whether the cache item has expired with
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// the given expiry duration from when it was stored.
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func (fm *FunctionMeta) Expired(expiry time.Duration) bool {
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return time.Now().After(fm.LastRefresh.Add(expiry))
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}
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// FunctionCache provides a cache of Function replica counts
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type FunctionCache struct {
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Cache map[string]*FunctionMeta
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Expiry time.Duration
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Sync sync.Mutex
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}
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// Set replica count for functionName
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func (fc *FunctionCache) Set(functionName string, replicas uint64) {
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fc.Sync.Lock()
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if _, exists := fc.Cache[functionName]; !exists {
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fc.Cache[functionName] = &FunctionMeta{}
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}
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entry := fc.Cache[functionName]
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entry.LastRefresh = time.Now()
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entry.Replicas = replicas
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fc.Sync.Unlock()
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}
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// Get replica count for functionName
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func (fc *FunctionCache) Get(functionName string) (uint64, bool) {
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replicas := uint64(0)
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hit := false
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fc.Sync.Lock()
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if val, exists := fc.Cache[functionName]; exists {
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replicas = val.Replicas
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hit = !val.Expired(fc.Expiry)
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}
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fc.Sync.Unlock()
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return replicas, hit
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}
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