darrenjs · September 4, 2018 06:49 · Sep 4, 2018 · Sep 4, 2018
diff --git a/python redis example → python_redis_example.py b/python redis example → python_redis_example.py
diff --git a/python redis example b/python redis example
@@ -0,0 +1,80 @@
+import redis
+import redis.sentinel
+
+import logging
+
+# TODO: would be useful to also
+def discover_redis_master(sentinel_addrs, redis_name):
+    """Use listed sentinels to find the redis master
+    """
+    sentinel = redis.sentinel.Sentinel(sentinel_addrs, socket_timeout=0.1)
+
+    master_addr = sentinel.discover_master(redis_name)
+
+    redis_client = sentinel.master_for(redis_name, socket_timeout=0.1)
+
+    if redis_client.ping():
+        return redis_client, master_addr
+    else:
+        raise Exception("failed to ping redis master")
+
+
+class SignupState:
+    CHKSUM_FAILED = "chksum mismatch"
+    NO_SUCH_REQUEST = "no such request"
+    ALREADY_VERIFIED = "already verified"
+    BACKEND_ERROR = "backend error"
+    SUCCESS = "success"
+    NOT_PENDING = "not pending"
+
+# TODO: add enum here (as class) for signup status
+
+# Attempt to update a redis signup record, to indicate that the user has clicked
+# in order to verify the signup.
+
+
+def update_signup_record_to_verified(r, user_key, user_chksum):
+    stored_obj = r.hgetall(user_key)
+    if not stored_obj:
+        logging.warning("{}: signup request not found".format(user_key))
+        return SignupState.NO_SUCH_REQUEST
+
+    status = stored_obj[b'status'].decode('utf-8')
+    chksum = stored_obj[b'chksum'].decode('utf-8')
+
+    # Check the user provided checksum matches the signup checksum.  This is
+    # needed so that an invalid (spoofing?) attempt to validate a signup account
+    # can be detected. So for signup to be successful, the user needs to new the
+    # signup key (which is guessable), the encoding key, and the original record
+    # checksum.
+    if user_chksum != chksum:
+        logging.warn("verify failed; chksum mismatch")
+        return SignupState.CHKSUM_FAILED
+
+    # TODO: return error codes in here, instead of exceptions
+    if (status == 'pending'):
+        rv = r.hset(user_key, 'status', 'verified')
+        if rv == 0:
+            logging.info("{}: signup status set to verified".format(user_key))
+            # TODO: here, set the state to 'verified'
+            return SignupState.SUCCESS
+        else:
+            logging.warn("hset expectedly returned value {}".format(rv))
+            return SignupState.BACKEND_ERROR
+    else:
+        logging.warn(
+            "{}: sign-up request is not in pending state, so cannot progress to verified; current state is '{}'".format(user_key, status))
+        return SignupState.NOT_PENDING
+
+
+def get_global_id_block(r, key, blocksize=100):
+    """Reserve a block of global id numbers.
+
+The usable inclusive range is returned in the tuple as (lower,upper).
+
+    """
+    assert isinstance(key, str)
+    assert isinstance(blocksize, int)
+    upper = r.incrby(key, max(blocksize, 1))
+    #lower = max(1, upper-blocksize)  # min valid id is 1
+    return (upper-blocksize, upper-1)
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