Merge pull request #43 from VEuPathDB/issue-42

Add method for retrieving a single file.

Author: Foxcapades

lib/src/main/kotlin/org/veupathdb/lib/compute/platform/AsyncPlatform.kt

@@ -203,6 +203,24 @@ object AsyncPlatform {
     return S3.getNonReservedFiles(jobID)
   }
 
+  /**
+   * Fetches the target file for the target job.
+   *
+   * If the target file does not exist, this method returns `null`.
+   *
+   * @param jobID Hash ID of the job whose file should be retrieved.
+   *
+   * @param fileName Name of the file to retrieve.
+   *
+   * @return A reference to the target file, if it exists, otherwise `null`.
+   *
+   * @since 1.5.0
+   */
+  fun getJobFile(jobID: HashID, fileName: String): JobFileReference? {
+    Log.debug("fetching target file \"{}\" for job {}", jobID, fileName)
+    return S3.getJobFile(jobID, fileName)
+  }
+
   /**
    * Deletes the target job only if it exists, is owned by the current service
    * or process, and is in a completed status.

lib/src/main/kotlin/org/veupathdb/lib/compute/platform/intern/s3/S3.kt

@@ -186,6 +186,35 @@ internal object S3 {
     return out
   }
 
+  /**
+   * Attempts to fetch the target file from the target workspace.
+   *
+   * If the target workspace is not found, an [IllegalStateException] will be
+   * thrown.
+   *
+   * If the target file is not found, `null` will be returned.
+   *
+   * @param jobID ID of the workspace from which the target job should be
+   * fetched.
+   *
+   * @return A handle on the target file, if it exists, or `null`.
+   *
+   * @since 1.5.0
+   */
+  @JvmStatic
+  fun getJobFile(jobID: HashID, fileName: String): JobFileReference? {
+    Log.debug("fetching target file \"{}\" for job {} in S3", fileName, jobID)
+
+    // Load the workspace
+    val ws = wsf[jobID] ?: throw IllegalStateException("attempted to fetch target file from nonexistent workspace $jobID")
+
+    // Sift through the files for one matching the target file name and return
+    // it (or null if none were found).
+    return ws.files()
+      .firstOrNull { it.name == fileName }
+      ?.let(::JobFileReferenceImpl)
+  }
+
   /**
    * Clears out the target workspace and marks it as `expired`.
    *