From 183b6340c69cd441fdb022df0662974e28e9e1c0 Mon Sep 17 00:00:00 2001
From: Menarul Alam <menarulalam@gmail.com>
Date: Mon, 3 Feb 2020 14:07:45 -0500
Subject: [PATCH] Added tenacity retry decorator with exponential backoff to
 function and updated requirements.txt

---
 report/firefox_code_coverage/codecoverage.py | 46 +++++++++++---------
 report/requirements.txt                      |  1 +
 2 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/report/firefox_code_coverage/codecoverage.py b/report/firefox_code_coverage/codecoverage.py
index 4cc6d9498..19a132bfa 100644
--- a/report/firefox_code_coverage/codecoverage.py
+++ b/report/firefox_code_coverage/codecoverage.py
@@ -15,6 +15,7 @@
 import requests
 
 from firefox_code_coverage import taskcluster
+from tenacity import retry, stop_after_attempt, wait_exponential
 
 FINISHED_STATUSES = ["completed", "failed", "exception"]
 ALL_STATUSES = FINISHED_STATUSES + ["unscheduled", "pending", "running"]
@@ -67,30 +68,33 @@ def _save_tasks(response):
     return tasks
 
 
-def download_binary(url, path, retries=5):
-    """Download a binary file from an url"""
-    for i in range(1, retries + 1):
+@retry(stop=stop_after_attempt(5), wait=wait_exponential(multiplier=1, max=64))
+def retry_download_binary(url, path):
+    """Download a binary file from an url with exponential backoff"""
+    try:
+        artifact = requests.get(url, stream=True)
+        artifact.raise_for_status()
+
+        with open(path, "wb") as f:
+            for chunk in artifact.iter_content(chunk_size=8192):
+                f.write(chunk)
+        return
+    except:  # noqa: E722
         try:
-            artifact = requests.get(url, stream=True)
-            artifact.raise_for_status()
-
-            with open(path, "wb") as f:
-                for chunk in artifact.iter_content(chunk_size=8192):
-                    f.write(chunk)
-            break
-        except:  # noqa: E722
-            try:
-                os.remove(path)
-            except OSError:
-                pass
-
-            if i == retries:
-                raise Exception(
-                    "Download failed after {} retries - {}".format(retries, url)
-                )
+            os.remove(path)
+        except OSError:
+            raise Exception
 
-            time.sleep(7 * i)
 
+def download_binary(url, path):
+    """Wrapper function for retry_download_binary which raises exception after max number of retries"""
+    try:
+        retry_download_binary(url, path)
+    except:
+        raise Exception(
+            "Download failed after {} retries - {}".format(str(retry_download_binary.retry.statistics["attempt_number"])
+                                                           , url)
+        )
 
 def download_artifact(task_id, artifact, artifacts_path):
     fname = os.path.join(
diff --git a/report/requirements.txt b/report/requirements.txt
index 28744c326..174d2f772 100644
--- a/report/requirements.txt
+++ b/report/requirements.txt
@@ -1 +1,2 @@
 taskcluster==24.2.0
+tenacity==6.0.0
\ No newline at end of file