1 files changed, 41 insertions, 0 deletions
diff --git a/third_party/python/taskcluster/taskcluster/aio/retry.py b/third_party/python/taskcluster/taskcluster/aio/retry.py
new file mode 100644
index 0000000000..d4f743f2d5
--- /dev/null
+++ b/third_party/python/taskcluster/taskcluster/aio/retry.py
@@ -0,0 +1,41 @@
+import logging
+import asyncio
+
+from .. import utils
+
+log = logging.getLogger(__name__)
+
+
+async def retry(maxRetries, tryFn):
+    """
+    Retry async `tryFn` based on `maxRetries`.  Each call to `tryFn` will pass a callable
+    which should be called with the exception object when an exception can be retried.
+    Exceptions raised from `tryFn` are treated as fatal.
+    """
+
+    retry = -1  # we plus first in the loop, and attempt 1 is retry 0
+    while True:
+        retry += 1
+
+        # if this isn't the first retry then we sleep
+        if retry > 0:
+            snooze = float(retry * retry) / 10.0
+            log.info('Sleeping %0.2f seconds for exponential backoff', snooze)
+            await asyncio.sleep(utils.calculateSleepTime(retry))
+
+        retriableException = None
+
+        def retryFor(exc):
+            nonlocal retriableException
+            retriableException = exc
+
+        res = await tryFn(retryFor)
+
+        if not retriableException:
+            return res
+
+        if retry < maxRetries:
+            log.warning(f'Retrying because of: {retriableException}')
+            continue
+
+        raise retriableException