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feat(api): adds caching layer to pepr endpoints (#402)
Co-authored-by: decleaver <85503726+decleaver@users.noreply.github.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,101 @@ | ||
| // SPDX-License-Identifier: Apache-2.0 | ||
| // SPDX-FileCopyrightText: 2024-Present The UDS Authors | ||
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| package monitor | ||
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| import ( | ||
| "bytes" | ||
| "net/http" | ||
| "sync" | ||
| "time" | ||
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| "github.com/defenseunicorns/uds-runtime/pkg/api/rest" | ||
| "github.com/zarf-dev/zarf/src/pkg/message" | ||
| ) | ||
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| // single instance of the pepr stream cache | ||
| var streamCache = NewCache() | ||
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| // Cache is a simple cache for pepr stream data, it can be invalidated by a timer and max size | ||
| type Cache struct { | ||
| buffer *bytes.Buffer | ||
| lock sync.RWMutex | ||
| timer *time.Timer | ||
| maxSize int | ||
| } | ||
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| // NewCache creates a new cache for pepr stream data | ||
| func NewCache() *Cache { | ||
| c := &Cache{ | ||
| buffer: &bytes.Buffer{}, | ||
| maxSize: 1024 * 1024 * 10, // 10MB | ||
| } | ||
| c.startResetTimer() | ||
| return c | ||
| } | ||
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| // startResetTimer starts a timer that resets the cache after 5 minutes | ||
| func (c *Cache) startResetTimer() { | ||
| c.timer = time.AfterFunc(5*time.Minute, func() { | ||
| message.Debug("Pepr cache invalidated by timer, resetting cache") | ||
| c.Reset() | ||
| c.startResetTimer() // restart timer | ||
| }) | ||
| } | ||
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| // Reset resets the cache | ||
| func (c *Cache) Reset() { | ||
| c.lock.Lock() | ||
| defer c.lock.Unlock() | ||
| message.Debug("Resetting pepr cache") | ||
| c.buffer.Reset() | ||
| } | ||
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| // Stop stops the cache timer | ||
| func (c *Cache) Stop() { | ||
| if c.timer != nil { | ||
| message.Debugf("Stopping pepr cache timer") | ||
| c.timer.Stop() | ||
| } | ||
| } | ||
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| // Get returns a deep copy of cached buffer | ||
| func (c *Cache) Get() *bytes.Buffer { | ||
| c.lock.RLock() | ||
| defer c.lock.RUnlock() | ||
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| if c.buffer == nil { | ||
| return nil | ||
| } | ||
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| return bytes.NewBuffer(c.buffer.Bytes()) | ||
| } | ||
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| // Set sets the cached buffer | ||
| func (c *Cache) Set(buffer *bytes.Buffer) { | ||
| if buffer.Len() > c.maxSize { | ||
| message.Debugf("Pepr cache size %d exceeds max size %d, resetting", buffer.Len(), c.maxSize) | ||
| c.Reset() | ||
| return | ||
| } | ||
| c.lock.Lock() | ||
| defer c.lock.Unlock() | ||
| c.buffer = buffer | ||
| } | ||
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| // Serve attempts to serve a cached response if available. | ||
| func (c *Cache) Serve(w http.ResponseWriter) { | ||
| cachedBuffer := c.Get() | ||
| if cachedBuffer == nil || cachedBuffer.Len() == 0 { | ||
| return | ||
| } | ||
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| rest.WriteHeaders(w) | ||
| _, err := w.Write(cachedBuffer.Bytes()) | ||
| if err != nil { | ||
| message.Warnf("Pepr cache failed to write response: %v", err) | ||
| return | ||
| } | ||
| w.(http.Flusher).Flush() | ||
| message.Debug("Used pepr cache to serve response") | ||
| } |
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