perf: query CI metadata only for pull request head

Landing checks only consume CI data from the final commit. Avoid
querying check suites and runs for every commit, which can exhaust the
GraphQL rate limit, and merge the head data after verifying its OID.

Signed-off-by: Filip Skokan <panva.ip@gmail.com>

Author: panva

lib/pr_data.js

@@ -60,11 +60,30 @@ export default class PRData {
       this.getThreadData(),
       this.getCommits()
     ]).then(() => {
+      this.mergeHeadCommitChecks();
       this.cli.stopSpinner(`Done loading data for ${prStr}`);
     });
     this.analyzeReviewers();
   }
 
+  mergeHeadCommitChecks() {
+    const headCommit = this.pr.headCommit?.nodes?.[0]?.commit;
+    delete this.pr.headCommit;
+
+    const lastCommit = this.commits.at(-1)?.commit;
+    if (headCommit === undefined && lastCommit === undefined) {
+      return;
+    }
+
+    if (headCommit?.oid !== lastCommit?.oid) {
+      throw new Error(
+        'Unable to match pull request head commit while loading data');
+    }
+
+    lastCommit.checkSuites = headCommit.checkSuites;
+    lastCommit.status = headCommit.status;
+  }
+
   analyzeReviewers() {
     this.reviewers = new ReviewAnalyzer(this).getReviewers();
   }

lib/queries/PR.gql

@@ -23,6 +23,35 @@ query PR($prid: Int!, $owner: String!, $repo: String!) {
           path
         }
       },
+      # CI data is only consumed for the pull request's head commit. Querying
+      # it for every commit multiplies the GraphQL rate-limit cost.
+      headCommit: commits(last: 1) {
+        nodes {
+          commit {
+            oid
+            checkSuites(first: 100) {
+              nodes {
+                app {
+                  slug
+                }
+                conclusion,
+                status,
+                checkRuns(first: 40) {
+                  nodes {
+                    name
+                    status
+                    conclusion
+                    detailsUrl
+                  }
+                }
+              }
+            }
+            status {
+              state
+            }
+          }
+        }
+      },
       title,
       baseRefName,
       headRefName,

lib/queries/PRCommits.gql

@@ -25,26 +25,6 @@ query Commits($prid: Int!, $owner: String!, $repo: String!, $after: String) {
             message
             messageHeadline
             authoredByCommitter
-            checkSuites(first: 100) {
-              nodes {
-                app {
-                  slug
-                }
-                conclusion,
-                status,
-                checkRuns(first: 40) {
-                  nodes {
-                    name
-                    status
-                    conclusion
-                    detailsUrl
-                  }
-                }
-              }
-            }
-            status {
-              state
-            }
           }
         }
       }

test/unit/graphql_queries.test.js

@@ -0,0 +1,26 @@
+import { readFileSync } from 'node:fs';
+import { describe, it } from 'node:test';
+import assert from 'node:assert';
+
+const prQuery = readFileSync(
+  new URL('../../lib/queries/PR.gql', import.meta.url), 'utf8');
+const commitsQuery = readFileSync(
+  new URL('../../lib/queries/PRCommits.gql', import.meta.url), 'utf8');
+
+describe('GraphQL queries', () => {
+  it('requests CI details only for the pull request head commit', () => {
+    const headCommitStart = prQuery.indexOf(
+      'headCommit: commits(last: 1)');
+    const headCommitEnd = prQuery.indexOf('\n      title,', headCommitStart);
+    const headCommitQuery = prQuery.slice(headCommitStart, headCommitEnd);
+
+    assert.notStrictEqual(headCommitStart, -1);
+    assert.notStrictEqual(headCommitEnd, -1);
+    assert.match(headCommitQuery, /checkSuites\(first: 100\)/);
+    assert.match(headCommitQuery, /checkRuns\(first: 40\)/);
+    assert.match(headCommitQuery, /status \{\s+state\s+\}/);
+    assert.doesNotMatch(commitsQuery, /checkSuites/);
+    assert.doesNotMatch(commitsQuery, /checkRuns/);
+    assert.doesNotMatch(commitsQuery, /\sstatus\s*\{/);
+  });
+});

test/unit/pr_data.test.js

@@ -23,6 +23,24 @@ function toRaw(obj) {
 const rawPR = toRaw({
   repository: { pullRequest: firstTimerPR }
 });
+const headCommitChecks = {
+  oid: oddCommits.at(-1).commit.oid,
+  checkSuites: {
+    nodes: [{
+      app: { slug: 'github-actions' },
+      status: 'COMPLETED',
+      conclusion: 'SUCCESS',
+      checkRuns: { nodes: [] }
+    }]
+  },
+  status: { state: 'SUCCESS' }
+};
+rawPR.repository.pullRequest.headCommit = {
+  nodes: [{ commit: toRaw(headCommitChecks) }]
+};
+
+const commitsWithHeadChecks = toRaw(oddCommits);
+Object.assign(commitsWithHeadChecks.at(-1).commit, headCommitChecks);
 
 describe('PRData', function() {
   const request = {
@@ -34,7 +52,8 @@ describe('PRData', function() {
     .withArgs('https://raw.githubusercontent.com/nodejs/node/HEAD/README.md')
     .returns(Promise.resolve(readme));
   request.text.returns(new Error('unknown query'));
-  request.gql.withArgs('PR').returns(Promise.resolve(rawPR));
+  request.gql.withArgs('PR').callsFake(
+    () => Promise.resolve(toRaw(rawPR)));
   request.gql.withArgs('Reviews').returns(
     Promise.resolve(toRaw(approvingReviews)));
   request.gql.withArgs('PRComments').returns(
@@ -53,7 +72,45 @@ describe('PRData', function() {
     assert.deepStrictEqual(data.pr, firstTimerPR, 'pr');
     assert.deepStrictEqual(data.reviews, approvingReviews, 'reviews');
     assert.deepStrictEqual(data.comments, commentsWithLGTM, 'comments');
-    assert.deepStrictEqual(data.commits, oddCommits, 'commits');
+    assert.deepStrictEqual(
+      data.commits, commitsWithHeadChecks, 'commits');
     assert.deepStrictEqual(data.reviewers, allGreenReviewers, 'reviewers');
   });
+
+  describe('mergeHeadCommitChecks', () => {
+    it('allows an empty commit list', () => {
+      const data = new PRData(argv, new TestCLI(), request);
+      data.pr = { headCommit: { nodes: [] } };
+      data.commits = [];
+
+      data.mergeHeadCommitChecks();
+
+      assert.deepStrictEqual(data.pr, {});
+      assert.deepStrictEqual(data.commits, []);
+    });
+
+    it('rejects missing head commit data', () => {
+      const data = new PRData(argv, new TestCLI(), request);
+      data.pr = {};
+      data.commits = toRaw(oddCommits);
+
+      assert.throws(
+        () => data.mergeHeadCommitChecks(),
+        /Unable to match pull request head commit/);
+    });
+
+    it('rejects a mismatched head commit', () => {
+      const data = new PRData(argv, new TestCLI(), request);
+      data.pr = {
+        headCommit: {
+          nodes: [{ commit: { ...headCommitChecks, oid: 'different' } }]
+        }
+      };
+      data.commits = toRaw(oddCommits);
+
+      assert.throws(
+        () => data.mergeHeadCommitChecks(),
+        /Unable to match pull request head commit/);
+    });
+  });
 });