// HandleQuery evaluates a query and returns an aggregated result set.
// See the README for the query JSON structure and the structure of the results.
func (s *Server) HandleQuery(w http.ResponseWriter, r *http.Request) {
start := time.Now()
query, err := gumshoe.ParseJSONQuery(r.Body)
if err != nil {
WriteError(w, err, http.StatusBadRequest)
return
}
rows, err := s.DB.GetQueryResult(query)
if err != nil {
WriteError(w, err, http.StatusBadRequest)
return
}
elapsed := time.Since(start)
statsd.Time("gumshoedb.query", elapsed)
durationMS := int(elapsed.Seconds() * 1000)
if r.URL.Query().Get("format") == "stream" {
// Streaming format:
// Header object: {"duration_ms": 123, "num_results", 234}
// Then num_rows row objects.
header := map[string]int{
"duration_ms": durationMS,
"num_rows": len(rows),
}
w.Header().Set("Content-Type", "application/json")
encoder := json.NewEncoder(w)
if err := encoder.Encode(header); err != nil {
WriteError(w, err, 500)
return
}
for i, row := range rows {
if err := encoder.Encode(row); err != nil {
WriteError(w, err, 500)
return
}
if i%1000 == 0 {
if f, ok := w.(http.Flusher); ok {
f.Flush()
}
}
}
return
}
results := map[string]interface{}{
"results": rows,
"duration_ms": durationMS,
}
WriteJSONResponse(w, results)
}
func (r *Router) HandleQuery(w http.ResponseWriter, req *http.Request) {
start := time.Now()
queryID := randomID() // used to make tracking a single query throught he logs easier
if req.URL.Query().Get("format") != "" {
WriteError(w, errors.New("non-standard query formats not supported"), 500)
return
}
query, err := gumshoe.ParseJSONQuery(req.Body)
if err != nil {
WriteError(w, err, http.StatusBadRequest)
return
}
Log.Printf("[%s] got query: %s", queryID, query)
for _, agg := range query.Aggregates {
if agg.Type == gumshoe.AggregateAvg {
// TODO(caleb): Handle as described in the doc.
WriteError(w, errors.New("average aggregates not handled by the router"), 500)
return
}
if !r.validColumnName(agg.Column) {
writeInvalidColumnError(w, agg.Column)
return
}
}
for _, grouping := range query.Groupings {
if !r.validColumnName(grouping.Column) {
writeInvalidColumnError(w, grouping.Column)
return
}
}
for _, filter := range query.Filters {
if !r.validColumnName(filter.Column) {
writeInvalidColumnError(w, filter.Column)
return
}
}
b, err := json.Marshal(query)
if err != nil {
panic("unexpected marshal error")
}
var (
wg wait.Group
mu sync.Mutex // protects result, resultMap
result []gumshoe.RowMap
// rest only for grouping case
groupingCol string
groupingColIntConv bool
resultMap = make(map[interface{}]*lockedRowMap)
)
if len(query.Groupings) > 0 {
groupingCol = query.Groupings[0].Name
groupingColIntConv = r.convertColumnToIntegral(query.Groupings[0].Column)
}
for i := range r.Shards {
i := i
wg.Go(func(_ <-chan struct{}) error {
shard := r.Shards[i]
url := "http://" + shard + "/query?format=stream"
resp, err := r.Client.Post(url, "application/json", bytes.NewReader(b))
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
return NewHTTPError(resp, shard)
}
decoder := json.NewDecoder(resp.Body)
var m map[string]int
if err := decoder.Decode(&m); err != nil {
return err
}
if len(query.Groupings) == 0 {
// non-grouping case
row := make(gumshoe.RowMap)
if err := decoder.Decode(&row); err != nil {
return err
}
mu.Lock()
if len(result) == 0 {
result = []gumshoe.RowMap{row}
} else {
r.mergeRows(result[0], row, query)
}
mu.Unlock()
if err := decoder.Decode(&row); err != io.EOF {
if err == nil {
return errors.New("got multiple results for a non-group-by query")
}
return err
}
return nil
}
// grouping case
var rowSize int
for {
row := make(gumshoe.RowMap, rowSize)
if err := decoder.Decode(&row); err != nil {
if err == io.EOF {
break
}
return err
}
rowSize = len(row)
groupByValue := row[groupingCol]
if groupingColIntConv && groupByValue != nil {
groupByValue = int64(groupByValue.(float64))
}
mu.Lock()
cur := resultMap[groupByValue]
if cur == nil {
resultMap[groupByValue] = &lockedRowMap{row: row}
mu.Unlock()
continue
}
// downgrade lock
cur.mu.Lock()
mu.Unlock()
r.mergeRows(cur.row, row, query)
cur.mu.Unlock()
}
return nil
})
}
if err := wg.Wait(); err != nil {
WriteError(w, err, http.StatusInternalServerError)
return
}
// For the grouping case, we need to flatten the results from resultMap.
if len(query.Groupings) > 0 {
for _, lr := range resultMap {
result = append(result, lr.row)
}
}
Log.Printf("[%s] fetched and merged query results from %d shards in %s (%d combined rows)",
queryID, len(r.Shards), time.Since(start), len(result))
WriteJSONResponse(w, Result{
Results: result,
DurationMS: int(time.Since(start).Seconds() * 1000),
})
}