Use db.download in trainer.py instead of manually reimplementing download and decompression (#739)

Fixes #733

scripts/trainer.py

@@ -4,44 +4,24 @@ import argparse
 import json
 import os
 from logging import INFO, basicConfig, getLogger
-from urllib.request import urlretrieve
 
 import zstandard
 
-from bugbug import get_bugbug_version, model
+from bugbug import bugzilla, db, model, repository
 from bugbug.models import get_model_class
 from bugbug.utils import CustomJsonEncoder
 
 basicConfig(level=INFO)
 logger = getLogger(__name__)
 
-BASE_URL = "https://index.taskcluster.net/v1/task/project.relman.bugbug.data_{}.{}/artifacts/public"
-
 
 class Trainer(object):
-    def decompress_file(self, path):
-        dctx = zstandard.ZstdDecompressor()
-        with open(f"{path}.zst", "rb") as input_f:
-            with open(path, "wb") as output_f:
-                dctx.copy_stream(input_f, output_f)
-        assert os.path.exists(path), "Decompressed file exists"
-
     def compress_file(self, path):
         cctx = zstandard.ZstdCompressor()
         with open(path, "rb") as input_f:
             with open(f"{path}.zst", "wb") as output_f:
                 cctx.copy_stream(input_f, output_f)
 
-    def download_db(self, db_type):
-        path = f"data/{db_type}.json"
-        formatted_base_url = BASE_URL.format(db_type, f"v{get_bugbug_version()}")
-        url = f"{formatted_base_url}/{db_type}.json.zst"
-        logger.info(f"Downloading {db_type} database from {url} to {path}.zst")
-        urlretrieve(url, f"{path}.zst")
-        assert os.path.exists(f"{path}.zst"), "Downloaded file exists"
-        logger.info(f"Decompressing {db_type} database")
-        self.decompress_file(path)
-
     def go(self, model_name):
         # Download datasets that were built by bugbug_data.
         os.makedirs("data", exist_ok=True)
@@ -54,10 +34,10 @@ class Trainer(object):
             or isinstance(model_obj, model.BugCoupleModel)
             or (hasattr(model_obj, "bug_data") and model_obj.bug_data)
         ):
-            self.download_db("bugs")
+            db.download(bugzilla.BUGS_DB, force=True)
 
         if isinstance(model_obj, model.CommitModel):
-            self.download_db("commits")
+            db.download(repository.COMMITS_DB, force=True)
 
         logger.info(f"Training *{model_name}* model")
         metrics = model_obj.train()