docs_update: Skip if a PR is already open

src/github.rs

@@ -2883,6 +2883,35 @@ impl GithubClient {
         };
         Ok(repo_id)
     }
+
+    /// Returns the number of issues or PRs that match the given query.
+    ///
+    /// See
+    /// <https://docs.github.com/en/search-github/searching-on-github/searching-issues-and-pull-requests>
+    /// and
+    /// <https://docs.github.com/en/search-github/getting-started-with-searching-on-github/understanding-the-search-syntax>
+    /// for the query syntax.
+    pub async fn issue_search_count(&self, query: &str) -> anyhow::Result<u64> {
+        let data = self
+            .graphql_query(
+                "query($query: String!) {
+                  search(query: $query, type: ISSUE, first: 0) {
+                    issueCount
+                  }
+                }",
+                serde_json::json!({
+                    "query": query,
+                }),
+            )
+            .await?;
+        if let serde_json::Value::Number(count) = &data["data"]["search"]["issueCount"]
+            && let Some(count) = count.as_u64()
+        {
+            Ok(count)
+        } else {
+            anyhow::bail!("expected issue count, got {data}");
+        }
+    }
 }
 
 #[derive(Debug, serde::Deserialize)]

src/handlers/docs_update.rs

@@ -65,6 +65,15 @@ impl Job for DocsUpdateJob {
 
 pub async fn docs_update() -> Result<Option<Issue>> {
     let gh = GithubClient::new_from_env();
+
+    if is_pr_already_open(&gh)
+        .await
+        .context("failed to determine if a PR is already open for updating the docs")?
+    {
+        tracing::trace!("pr is already open");
+        return Ok(None);
+    }
+
     let dest_repo = gh.repository(DEST_REPO).await?;
     let work_repo = gh.repository(WORK_REPO).await?;
 
@@ -78,6 +87,15 @@ pub async fn docs_update() -> Result<Option<Issue>> {
     Ok(Some(create_pr(&gh, &dest_repo, &updates).await?))
 }
 
+async fn is_pr_already_open(gh: &GithubClient) -> Result<bool> {
+    let count = gh
+        .issue_search_count(&format!(
+            "repo:{DEST_REPO} is:pr is:open author:rustbot head:{BRANCH_NAME}"
+        ))
+        .await?;
+    Ok(count != 0)
+}
+
 struct Update {
     path: String,
     new_hash: String,