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// skate-cluster takes the (tab) output of skate-map (plus sort) and generates
// a "cluster" document, grouping docs by key. Can do some pre-filtering (e.g.
// require refs and release docs in a single cluster).
//
// For example, this:
//
// id123 somekey123 {"a":"b", ...}
// id391 somekey123 {"x":"y", ...}
//
// would turn into (a single line containing all docs with the same key).
//
// {"k": "somekey123", "v": [{"a":"b", ...},{"x":"y",...}]}
//
// A single line cluster is easier to parallelize (e.g. for verification, etc.).
package main
import (
"bufio"
"flag"
"fmt"
"io"
"log"
"os"
"strings"
)
var (
keyField = flag.Int("k", 2, "which column contains the key (one based)")
docField = flag.Int("d", 3, "which column contains the doc (one based)")
minClusterSize = flag.Int("min", 2, "minimum cluster size")
maxClusterSize = flag.Int("max", 100000, "maximum cluster size")
requireBoth = flag.Bool("both", false,
"require at least one ref and one non-ref item present in the cluster, implies -min 2")
dropEmptyKeys = flag.Bool("D", false, "drop empty keys")
delimiter = flag.String("d", "\t", "field delimiter")
)
func main() {
flag.Parse()
var (
br = bufio.NewReader(os.Stdin)
bw = bufio.NewWriter(os.Stdout)
prev, key, doc string
batch, fields []string
keyIndex = *keyField - 1
docIndex = *docField - 1
line string
err error
)
defer bw.Flush()
for {
line, err = br.ReadString('\n')
if err == io.EOF {
break
}
if err != nil {
log.Fatal(err)
}
fields = strings.Split(line, *delimiter)
if len(fields) <= keyIndex || len(fields) <= docIndex {
log.Fatalf("line has only %d fields", len(fields))
}
key = strings.TrimSpace(fields[keyIndex])
if *dropEmptyKeys && len(key) == 0 {
continue
}
doc = strings.TrimSpace(fields[docIndex])
if prev != key {
if err := writeBatch(bw, key, batch); err != nil {
log.Fatal(err)
}
batch = nil
}
prev = key
batch = append(batch, doc)
}
if err := writeBatch(bw, prev, batch); err != nil {
log.Fatal(err)
}
}
// containsBoth return true, if we have a ref and a non-ref item in the batch.
func containsBoth(batch []string) bool {
var numRef int
for _, doc := range batch {
// This is brittle (but faster). Most JSON should be in compact form,
// and there the following chars are by convention added to distinguish
// a release coming from a reference doc from other releases.
if strings.Contains(doc, `"status":"ref"`) {
numRef++
}
}
return numRef > 0 && numRef < len(batch)
}
// writeBatch writes out a single line containing the key and the cluster values.
func writeBatch(w io.Writer, key string, batch []string) (err error) {
if len(batch) == 0 {
return nil
}
if len(batch) < *minClusterSize || len(batch) > *maxClusterSize {
return nil
}
if *requireBoth && !containsBoth(batch) {
return nil
}
// This is brittle (and fast), but all items in a batch are valid JSON
// objects, hence, the following will be valid JSON as well, or will it?
// The key should not contain a quote.
_, err = fmt.Fprintf(w, "{\"k\": \"%s\", \"v\": [%s]}\n", key, strings.Join(batch, ","))
return
}
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