Add retry mechanism with backoff (#1494)

1 files changed, 40 insertions, 0 deletions

diff --git a/redis/retry.py b/redis/retry.py
new file mode 100644
index 0000000..cd06a23
--- /dev/null
+++ b/redis/retry.py
@@ -0,0 +1,40 @@
+from time import sleep
+
+from redis.exceptions import ConnectionError, TimeoutError
+
+
+class Retry:
+    """Retry a specific number of times after a failure"""
+
+    def __init__(self, backoff, retries,
+                 supported_errors=(ConnectionError, TimeoutError)):
+        """
+        Initialize a `Retry` object with a `Backoff` object
+        that retries a maximum of `retries` times.
+        You can specify the types of supported errors which trigger
+        a retry with the `supported_errors` parameter.
+        """
+        self._backoff = backoff
+        self._retries = retries
+        self._supported_errors = supported_errors
+
+    def call_with_retry(self, do, fail):
+        """
+        Execute an operation that might fail and returns its result, or
+        raise the exception that was thrown depending on the `Backoff` object.
+        `do`: the operation to call. Expects no argument.
+        `fail`: the failure handler, expects the last error that was thrown
+        """
+        self._backoff.reset()
+        failures = 0
+        while True:
+            try:
+                return do()
+            except self._supported_errors as error:
+                failures += 1
+                fail(error)
+                if failures > self._retries:
+                    raise error
+                backoff = self._backoff.compute(failures)
+                if backoff > 0:
+                    sleep(backoff)