func (b *blueflood) FetchSingleSeries(request api.FetchSeriesRequest) (api.Timeseries, error) {
sampler, ok := samplerMap[request.SampleMethod]
if !ok {
return api.Timeseries{}, fmt.Errorf("unsupported SampleMethod %s", request.SampleMethod.String())
}
queryUrl, err := b.constructURL(request, sampler)
if err != nil {
return api.Timeseries{}, err
}
// Issue GET to fetch metrics
parsedResult, err := b.fetch(request, queryUrl)
if err != nil {
return api.Timeseries{}, err
}
values := processResult(parsedResult, request.Timerange, sampler)
log.Debugf("Constructed timeseries from result: %v", values)
return api.Timeseries{
Values: values,
TagSet: request.Metric.TagSet,
}, nil
}
// Blueflood keys the resolution param to a java enum, so we have to convert
// between them.
//
func (c Config) bluefloodResolution(
desiredResolution time.Duration,
startMs int64) Resolution {
log.Debugf("Desired resolution in minutes: %d\n", desiredResolution/time.Minute)
now := c.TimeSource().Unix() * 1000 //Milliseconds
// Choose the appropriate resolution based on TTL, fetching the highest resolution data we can
//
age := time.Duration(now-startMs) * time.Millisecond //Age in milliseconds
log.Debugf("The age in minutes of the start time %d\n", age/time.Minute)
for _, current := range Resolutions {
maxAge := c.oldestViableDataForResolution(current)
// log.Debugf("Oldest age? %+v\n", maxAge)
log.Debugf("Considering resolution %v\n", current)
log.Debugf("Oldest conceivable data is %v\n", maxAge)
log.Debugf("Is the desired resolution less than or equal to the current? %b\n", desiredResolution <= current.duration)
log.Debugf("Is the start time within the TTL window? %b\n", age < maxAge)
// If the desired resolution is less than or equal to the
// current resolution and is the distance from now to the oldest
// viable data still available?
if desiredResolution <= current.duration &&
age < maxAge {
log.Debugf("Choosing resolution: %v\n", current)
return current
}
}
// If none of the above matched, we choose the coarsest
return Resolutions[len(Resolutions)-1]
}
// Blueflood keys the resolution param to a java enum, so we have to convert
// between them.
func (c Config) bluefloodResolution(
desiredResolution time.Duration,
startMs int64) Resolution {
now := time.Now().Unix() * 1000
// Choose the appropriate resolution based on TTL, fetching the highest resolution data we can
for _, current := range Resolutions {
age := time.Duration(now-startMs) * time.Millisecond
maxAge := c.getTTL(current)
log.Debugf("Desired (s): %d\n", desiredResolution/time.Second)
log.Debugf("Current (s): %d\n", current.duration/time.Second)
log.Debugf("age (s): %d\n", age/time.Second)
log.Debugf("ttl (s): %d\n", maxAge/time.Second)
if desiredResolution <= current.duration &&
age < c.getTTL(current) {
return current
}
}
// return the coarsest resolution.
return Resolutions[len(Resolutions)-1]
}
// fetches from the backend. on error, it returns an instance of api.TimeseriesStorageError
func (b *Blueflood) fetch(request api.FetchTimeseriesRequest, queryUrl *url.URL) (queryResponse, []byte, error) {
log.Debugf("Blueflood fetch: %s", queryUrl.String())
success := make(chan queryResponse, 1)
failure := make(chan error, 1)
timeout := time.After(b.config.Timeout)
var rawResponse []byte
go func() {
resp, err := b.client.Get(queryUrl.String())
if err != nil {
failure <- api.TimeseriesStorageError{request.Metric, api.FetchIOError, "error while fetching - http connection"}
return
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
rawResponse = body
if err != nil {
failure <- api.TimeseriesStorageError{request.Metric, api.FetchIOError, "error while fetching - reading"}
return
}
log.Debugf("Fetch result: %s", string(body))
var parsedJson queryResponse
err = json.Unmarshal(body, &parsedJson)
// Construct a Timeseries from the result:
if err != nil {
failure <- api.TimeseriesStorageError{request.Metric, api.FetchIOError, "error while fetching - json decoding"}
return
}
success <- parsedJson
}()
select {
case response := <-success:
return response, rawResponse, nil
case err := <-failure:
return queryResponse{}, rawResponse, err
case <-timeout:
return queryResponse{}, rawResponse, api.TimeseriesStorageError{request.Metric, api.FetchTimeoutError, ""}
}
}
func (b *Blueflood) FetchSingleTimeseries(request api.FetchTimeseriesRequest) (api.Timeseries, error) {
defer request.Profiler.RecordWithDescription("Blueflood FetchSingleTimeseries", request.Metric.String())()
sampler, ok := samplerMap[request.SampleMethod]
if !ok {
return api.Timeseries{}, fmt.Errorf("unsupported SampleMethod %s", request.SampleMethod.String())
}
queryResolution := b.config.bluefloodResolution(
request.Timerange.Resolution(),
request.Timerange.Start(),
)
log.Debugf("Blueflood resolution: %s\n", queryResolution.String())
// Sample the data at the given `queryResolution`
queryUrl, err := b.constructURL(request, sampler, queryResolution)
if err != nil {
return api.Timeseries{}, err
}
rawResults := make([][]byte, 1)
parsedResult, rawResult, err := b.fetch(request, queryUrl)
rawResults[0] = rawResult
if err != nil {
return api.Timeseries{}, err
}
// combinedResult contains the requested data, along with higher-resolution data intended to fill in gaps.
combinedResult := parsedResult.Values
// Sample the data at the FULL resolution.
// We clip the timerange so that it's only #{config.FullResolutionOverlap} seconds long.
// This limits the amount of data to be fetched.
fullResolutionParsedResult := func() []metricPoint {
// If an error occurs, we just return nothing. We don't return the error.
// This is so that errors while fetching the FULL-resolution data don't impact the requested data.
fullResolutionRequest := request // Copy the request
if request.Timerange.End()-request.Timerange.Start() > b.config.FullResolutionOverlap*1000 {
// Clip the timerange
newTimerange, err := api.NewSnappedTimerange(request.Timerange.End()-b.config.FullResolutionOverlap*1000, request.Timerange.End(), request.Timerange.ResolutionMillis())
if err != nil {
log.Infof("FULL resolution data errored while building timerange: %s", err.Error())
return nil
}
fullResolutionRequest.Timerange = newTimerange
}
fullResolutionQueryURL, err := b.constructURL(fullResolutionRequest, sampler, ResolutionFull)
if err != nil {
log.Infof("FULL resolution data errored while building url: %s", err.Error())
return nil
}
fullResolutionParsedResult, rawResult, err := b.fetch(request, fullResolutionQueryURL)
rawResults = append(rawResults, rawResult)
if err != nil {
log.Infof("FULL resolution data errored while parsing result: %s", err.Error())
return nil
}
// The higher-resolution data will likely overlap with the requested data.
// This isn't a problem - the requested, higher-resolution data will be downsampled by this code.
// This downsampling should arrive at the same answer as Blueflood's built-in rollups.
return fullResolutionParsedResult.Values
}()
combinedResult = append(combinedResult, fullResolutionParsedResult...)
values := processResult(combinedResult, request.Timerange, sampler, queryResolution)
log.Debugf("Constructed timeseries from result: %v", values)
if request.UserSpecifiableConfig.IncludeRawData {
return api.Timeseries{
Values: values,
TagSet: request.Metric.TagSet,
Raw: rawResults,
}, nil
} else {
return api.Timeseries{
Values: values,
TagSet: request.Metric.TagSet,
}, nil
}
}