Method triggerBuild

packages/cli/src/util/dev/server.ts:1664–1721

(
    match: BuildMatch,
    requestPath: string | null,
    req: http.IncomingMessage | null,
    vercelConfig: VercelConfig,
    previousBuildResult?: BuildResult,
    filesChanged?: string[],
    filesRemoved?: string[]
  )

  }

  async triggerBuild(
    match: BuildMatch,
    requestPath: string | null,
    req: http.IncomingMessage | null,
    vercelConfig: VercelConfig,
    previousBuildResult?: BuildResult,
    filesChanged?: string[],
    filesRemoved?: string[]
  ) {
    // If the requested asset wasn't found in the match's
    // outputs then trigger a build
    const buildKey =
      requestPath === null
        ? match.entrypoint
        : `${match.entrypoint}-${requestPath}`;
    let buildPromise = this.inProgressBuilds.get(buildKey);
    if (buildPromise) {
      // A build for `buildKey` is already in progress, so don't trigger
      // another rebuild for this request - just wait on the existing one.
      let msg = `De-duping build "${buildKey}"`;
      if (req) {
        msg += ` for "${req.method} ${req.url}"`;
      }
      output.debug(msg);
    } else {
      if (previousBuildResult) {
        // Tear down any `output` assets from a previous build, so that they
        // are not available to be served while the rebuild is in progress.
        for (const [name] of Object.entries(previousBuildResult.output)) {
          output.debug(`Removing asset "${name}"`);
          delete match.buildOutput[name];
          // TODO: shut down Lambda instance
        }
      }
      let msg = `Building asset "${buildKey}"`;
      if (req) {
        msg += ` for "${req.method} ${req.url}"`;
      }
      output.debug(msg);
      buildPromise = executeBuild(
        vercelConfig,
        this,
        this.files,
        match,
        requestPath,
        false,
        filesChanged,
        filesRemoved
      );
      this.inProgressBuilds.set(buildKey, buildPromise);
    }
    try {
      await buildPromise;
    } finally {
      output.debug(`Built asset ${buildKey}`);
      this.inProgressBuilds.delete(buildKey);
    }
  }