// Remove entry from request log and compact
func (this *RequestLog) ditch(id string) errors.Error {
cacheNum := util.HashString(id, _CACHES)
this.locks[cacheNum].Lock()
defer this.locks[cacheNum].Unlock()
logMap, ok := this.requestMaps[cacheNum][id]
if ok {
delete(this.requestMaps[cacheNum], id)
l := len(this.requestMaps[cacheNum])
// Nature abhors a vacuum!
// We copy the last map entry onto the currently empty entry.
// This is a quick way to keep the two caches in sync without
// reallocating memory and / or copying huge quantities of data,
// but it does mean that for scans occurring during deletes,
// later entries might be skipped.
// Given the fact that deletes will likely purge huge numbers of
// entries, copying subslices on a per deleted row basis has the
// potential for a significant bottleneck.
// Given the huge benefit in lock contention and memory usage, we
// are willing to take that risk.
if logMap.logIdx < l {
this.requestCaches[cacheNum][logMap.logIdx] = this.requestCaches[cacheNum][l]
newMap := this.requestMaps[cacheNum][this.requestCaches[cacheNum][l].RequestId]
newMap.logIdx = logMap.logIdx
}
return nil
} else {
return errors.NewSystemStmtNotFoundError(nil, id)
}
}
func (this *RequestLog) add(entry *RequestLogEntry) {
var requestLogMap RequestLogMap
cacheNum := util.HashString(entry.RequestId, _CACHES)
this.locks[cacheNum].Lock()
defer this.locks[cacheNum].Unlock()
mLen := len(this.requestMaps[cacheNum])
cLen := len(this.requestCaches[cacheNum])
// Resize the slice if required
// The map gets handled automatically
// TODO handle memory allocation failures
if mLen >= cLen {
caches := make([]*RequestLogEntry, cLen*2)
copy(caches, this.requestCaches[cacheNum])
this.requestCaches[cacheNum] = caches
}
requestLogMap.logEntry = entry
requestLogMap.logIdx = mLen
this.requestMaps[cacheNum][entry.RequestId] = requestLogMap
this.requestCaches[cacheNum][mLen] = entry
}
func (this *RequestLog) get(id string) *RequestLogEntry {
cacheNum := util.HashString(id, _CACHES)
this.locks[cacheNum].RLock()
defer this.locks[cacheNum].RUnlock()
return this.requestMaps[cacheNum][id].logEntry
}