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New proxy server counting logic for agent and server #634
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206e457
Add static and cached server counters
carreter dfffce9
Consistent file naming
carreter 2a8282e
Wire in new ServerCounter to proxy agent
carreter fa72e2d
Wire in new ServerCounter to proxy server
carreter 2cb1d7e
Set default ServerCounter on agent
carreter 4bc512d
Remove empty file
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,43 @@ | ||
| package servercounter | ||
|
|
||
| import ( | ||
| "time" | ||
|
|
||
| "k8s.io/klog/v2" | ||
| ) | ||
|
|
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| // A CachedServerCounter wraps a ServerCounter to cache its server count value. | ||
| // Cache refreshes occur when CountServers() is called after a user-configurable | ||
| // cache expiration duration. | ||
| type CachedServerCounter struct { | ||
| inner ServerCounter | ||
| cachedCount int | ||
| expiration time.Duration | ||
| lastRefresh time.Time | ||
| } | ||
|
|
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| // CountServers returns the last cached server count and updates the cached count | ||
| // if it has expired since the last call. | ||
| func (csc *CachedServerCounter) CountServers() int { | ||
| // Refresh the cache if expiry time has passed since last call. | ||
| if time.Now().Sub(csc.lastRefresh) >= csc.expiration { | ||
| newCount := csc.inner.CountServers() | ||
| if newCount != csc.cachedCount { | ||
| klog.Infof("updated cached server count from %v to %v", csc.cachedCount, newCount) | ||
| } | ||
| csc.lastRefresh = time.Now() | ||
| } | ||
|
|
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| return csc.cachedCount | ||
| } | ||
|
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| // NewCachedServerCounter creates a new CachedServerCounter with a given expiration | ||
| // time wrapping the provided ServerCounter. | ||
| func NewCachedServerCounter(serverCounter ServerCounter, expiration time.Duration) *CachedServerCounter { | ||
| return &CachedServerCounter{ | ||
| inner: serverCounter, | ||
| cachedCount: serverCounter.CountServers(), | ||
| expiration: expiration, | ||
| lastRefresh: time.Now(), | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,52 @@ | ||
| package servercounter | ||
|
|
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| import ( | ||
| "testing" | ||
| "time" | ||
| ) | ||
|
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| type MockServerCounter struct { | ||
| NumCalls int | ||
| Count int | ||
| } | ||
|
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| func (msc *MockServerCounter) CountServers() int { | ||
| msc.NumCalls += 1 | ||
| return msc.Count | ||
| } | ||
|
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| func TestCachedServerCounter(t *testing.T) { | ||
| initialCount := 3 | ||
| mockCounter := &MockServerCounter{NumCalls: 0, Count: initialCount} | ||
|
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| cacheExpiry := time.Second // This can be tuned down to make this test run faster, just don't make it too small! | ||
| cachedCounter := NewCachedServerCounter(mockCounter, cacheExpiry) | ||
|
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| if mockCounter.NumCalls != 1 { | ||
| t.Errorf("inner server counter have been called once during cached counter creation, got %v calls isntead", mockCounter.NumCalls) | ||
| } | ||
|
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| // Updates in the underlying ServerCounter should not matter until the cache expires. | ||
| callAttemptsWithoutRefresh := 5 | ||
| for i := 0; i < callAttemptsWithoutRefresh; i++ { | ||
| mockCounter.Count = 100 + i | ||
| time.Sleep(cacheExpiry / time.Duration(callAttemptsWithoutRefresh) / time.Duration(2)) | ||
| got := cachedCounter.CountServers() | ||
| if got != initialCount { | ||
| t.Errorf("server count should not have been updated yet; wanted: %v, got %v", initialCount, got) | ||
| } else if mockCounter.NumCalls != 1 { | ||
| t.Errorf("inner server counter should not have been called yet; expected 1 call, got %v instead", mockCounter.NumCalls) | ||
| } | ||
| } | ||
|
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| // Once the cache expires, the cached count should update by calling the underlying | ||
| // ServerCounter. | ||
| mockCounter.Count = 5 | ||
| time.Sleep(cacheExpiry) | ||
| got := cachedCounter.CountServers() | ||
| if got != initialCount { | ||
| t.Errorf("server count should have been updated yet; wanted: %v, got %v", mockCounter.Count, got) | ||
| } else if mockCounter.NumCalls != 2 { | ||
| t.Errorf("inner server counter should have been called one more time; expected 2 calls, got %v instead", mockCounter.NumCalls) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,14 @@ | ||
| package servercounter | ||
|
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| // A ServerCounter counts the number of available proxy servers. | ||
| type ServerCounter interface { | ||
| CountServers() int | ||
| } | ||
|
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| // A StaticServerCounter stores a static server count. | ||
| type StaticServerCounter int | ||
|
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| // CountServers returns the current (static) proxy server count. | ||
| func (sc StaticServerCounter) CountServers() int { | ||
| return int(sc) | ||
| } |
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Should chat on this. During certain events with multiple KASs/Konnectivity servers we can get different server counts from different servers.
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Yeah, @avrittrohwer also raised this issue. One potential solution would be to cache the last n received server counts and take the highest value. Ultimately this gets solved by having proxy agents count the leases themselves.