git-codereview: batch GerritChange info fetches during pending

This speeds pending a bit by reducing the number of round trips
to the Gerrit server when you have a stack of CLs.

Change-Id: I456e1a8739b9b6586f4e05c1a5442f402e440a79
Reviewed-on: https://go-review.googlesource.com/67571
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/git-codereview/branch.go b/git-codereview/branch.go
index 13193ff..982c739 100644
--- a/git-codereview/branch.go
+++ b/git-codereview/branch.go
@@ -7,6 +7,7 @@ package main
 import (
 	"bytes"
 	"fmt"
+	"net/url"
 	"os"
 	"os/exec"
 	"regexp"
@@ -322,6 +323,33 @@ func (b *Branch) GerritChange(c *Commit, extra ...string) (*GerritChange, error)
 	return readGerritChange(id)
 }
 
+// GerritChange returns the change metadata from the Gerrit server
+// for the given changes, which each be be the result of fullChangeID(b, c) for some c.
+// The extra strings are passed to the Gerrit API request as o= parameters,
+// to enable additional information. Typical values include "LABELS" and "CURRENT_REVISION".
+// See https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html for details.
+func (b *Branch) GerritChanges(ids []string, extra ...string) ([][]*GerritChange, error) {
+	q := ""
+	for _, id := range ids {
+		if q != "" {
+			q += "&"
+		}
+		if strings.HasSuffix(id, "~") {
+			// result of fullChangeID(b, c) with missing Change-Id; don't send
+			q += "q=is:closed+is:open" // cannot match anything
+			continue
+		}
+		q += "q=change:" + url.QueryEscape(id)
+	}
+	if q == "" {
+		return nil, fmt.Errorf("no changes found")
+	}
+	for _, x := range extra {
+		q += "&o=" + url.QueryEscape(x)
+	}
+	return readGerritChanges(q)
+}
+
 // CommitByRev finds a unique pending commit by its git <rev>.
 // It dies if rev cannot be resolved to a commit or that commit is not
 // pending on b using the action ("mail", "submit") in the failure message.