import log: flush on write; close on crash (#337)

beets/importer.py

@@ -57,6 +57,7 @@ def tag_log(logfile, status, path):
     """
     if logfile:
         print >>logfile, '%s %s' % (status, path)
+        logfile.flush()
 
 def log_choice(config, task):
     """Logs the task's current choice if it should be logged.

beets/ui/commands.py

@@ -593,35 +593,37 @@ def import_files(lib, paths, copy, write, autot, logpath, art, threaded,
     if resume is None and quiet:
         resume = False
 
-    # Perform the import.
-    importer.run_import(
-        lib = lib,
-        paths = paths,
-        resume = resume,
-        logfile = logfile,
-        color = color,
-        quiet = quiet,
-        quiet_fallback = quiet_fallback,
-        copy = copy,
-        write = write,
-        art = art,
-        delete = delete,
-        threaded = threaded,
-        autot = autot,
-        choose_match_func = choose_match,
-        should_resume_func = should_resume,
-        singletons = singletons,
-        timid = timid,
-        choose_item_func = choose_item,
-        query = query,
-        incremental = incremental,
-        ignore = ignore,
-    )
+    try:
+        # Perform the import.
+        importer.run_import(
+            lib = lib,
+            paths = paths,
+            resume = resume,
+            logfile = logfile,
+            color = color,
+            quiet = quiet,
+            quiet_fallback = quiet_fallback,
+            copy = copy,
+            write = write,
+            art = art,
+            delete = delete,
+            threaded = threaded,
+            autot = autot,
+            choose_match_func = choose_match,
+            should_resume_func = should_resume,
+            singletons = singletons,
+            timid = timid,
+            choose_item_func = choose_item,
+            query = query,
+            incremental = incremental,
+            ignore = ignore,
+        )
     
-    # If we were logging, close the file.
-    if logfile:
-        print >>logfile, ''
-        logfile.close()
+    finally:
+        # If we were logging, close the file.
+        if logfile:
+            print >>logfile, ''
+            logfile.close()
 
     # Emit event.
     plugins.send('import', lib=lib, paths=paths)

docs/changelog.rst

@@ -33,6 +33,8 @@ Changelog
   layer. See :ref:`writing-plugins`.
 * A reasonable error message is now shown when the import log file cannot be
   opened.
+* The import log file is now flushed and closed properly so that it can be used
+  to monitor import progress, even when the import crashes.
 * Fix a bug in the ``rewrite`` plugin that broke the use of multiple rules for
   a single field.
 * Fix a crash with non-ASCII characters in bytestring metadata fields (e.g.,