From 05b4220e61c6fc4855042c599a7296b87981c647 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Mon, 25 May 2020 12:01:09 -0400
Subject: [PATCH] some database interaction improvements
removing the operation-id may not actually be an improvement ... it is a
simplification, though. However it requires us to load all the rows into
python and then send them back to the database instead of only loading them.
I thought removing the operation-id from the in-use table would be a win and
maybe it is but not for the reason I thought - sqlite3 emits the same code
whether you do `in [foo]` or `in (select x from [foo])` as far as I can tell.
Still, I like the simplification so we'll go with it for now.
---
src/_zkapauthorizer/model.py | 45 ++++++++++++++++--------------------
1 file changed, 20 insertions(+), 25 deletions(-)
diff --git a/src/_zkapauthorizer/model.py b/src/_zkapauthorizer/model.py
index 3b23a91..66dcb12 100644
--- a/src/_zkapauthorizer/model.py
+++ b/src/_zkapauthorizer/model.py
@@ -17,9 +17,6 @@ This module implements models (in the MVC sense) for the client side of
the storage plugin.
"""
-from uuid import (
- uuid4,
-)
from functools import (
wraps,
)
@@ -154,18 +151,23 @@ def open_and_initialize(path, connect=None):
# upgrade logic because we re-create them on every connection.
conn.execute(
"""
+ -- Track tokens in use by the process holding this connection.
CREATE TEMPORARY TABLE [in-use] (
[unblinded-token] text, -- The base64 encoded unblinded token.
- [operation-id] text, -- A unique identifier for a group of tokens in-use together.
PRIMARY KEY([unblinded-token])
-- A foreign key on unblinded-token to [unblinded-tokens]([token])
-- would be alright - however SQLite3 foreign key constraints
-- can't cross databases (and temporary tables are considered to
- -- be in a different database than normal tables). ) """,
+ -- be in a different database than normal tables).
+ )
+ """,
)
conn.execute(
"""
+ -- Track tokens that we want to remove from the database. Mainly just
+ -- works around the awkward DB-API interface for dealing with deleting
+ -- many rows.
CREATE TEMPORARY TABLE [to-discard] (
[unblinded-token] text
)
@@ -173,18 +175,13 @@ def open_and_initialize(path, connect=None):
)
conn.execute(
"""
+ -- Track tokens that we want to remove from the [in-use] set. Similar
+ -- to [to-discard].
CREATE TEMPORARY TABLE [to-reset] (
[unblinded-token] text
)
""",
)
- conn.execute(
- """
- CREATE TEMPORARY TABLE [extracting] (
- [token] text
- )
- """,
- )
return conn
@@ -515,27 +512,25 @@ class VoucherStore(object):
# provoke undesirable behavior from the database.
raise NotEnoughTokens()
- operation_id = unicode(uuid4())
cursor.execute(
"""
- INSERT INTO [in-use]
- SELECT [token], ?
+ SELECT [token]
FROM [unblinded-tokens]
- WHERE [token] NOT IN (SELECT [unblinded-token] FROM [in-use])
+ WHERE [token] NOT IN [in-use]
LIMIT ?
""",
- (operation_id, count),
+ (count,),
)
- if cursor.rowcount < count:
+ texts = cursor.fetchall()
+ if len(texts) < count:
raise NotEnoughTokens()
- cursor.execute(
+ cursor.executemany(
"""
- SELECT [unblinded-token] FROM [in-use] WHERE [operation-id] = ?
+ INSERT INTO [in-use] VALUES (?)
""",
- (operation_id,),
+ texts,
)
- texts = cursor.fetchall()
return list(
UnblindedToken(t)
for (t,)
@@ -562,13 +557,13 @@ class VoucherStore(object):
cursor.execute(
"""
DELETE FROM [in-use]
- WHERE [unblinded-token] IN (SELECT [unblinded-token] FROM [to-discard])
+ WHERE [unblinded-token] IN [to-discard]
""",
)
cursor.execute(
"""
DELETE FROM [unblinded-tokens]
- WHERE [token] IN (SELECT [unblinded-token] FROM [to-discard])
+ WHERE [token] IN [to-discard]
""",
)
cursor.execute(
@@ -629,7 +624,7 @@ class VoucherStore(object):
cursor.execute(
"""
DELETE FROM [in-use]
- WHERE [unblinded-token] IN (SELECT [unblinded-token] FROM [to-reset])
+ WHERE [unblinded-token] IN [to-reset]
""",
)
cursor.execute(
--
GitLab