From: Rob Kinninmont <robk@allmydata.com>
Date: Fri, 1 Dec 2006 10:04:54 +0000 (-0700)
Subject: split 'Bucket' into separate subclasses for read and write
X-Git-Tag: tahoe_v0.1.0-0-UNSTABLE~503
X-Git-Url: https://git.rkrishnan.org/specifications/%5B/%5D%20//%22%22?a=commitdiff_plain;h=14a2dbd5535a5d82b26152dcd824b1ae2b52f3ce;p=tahoe-lafs%2Ftahoe-lafs.git

split 'Bucket' into separate subclasses for read and write
---

diff --git a/allmydata/bucketstore.py b/allmydata/bucketstore.py
index 84b7083a..3c226dee 100644
--- a/allmydata/bucketstore.py
+++ b/allmydata/bucketstore.py
@@ -16,7 +16,6 @@ class BucketStore(service.MultiService, Referenceable):
         service.MultiService.__init__(self)
         self._store_dir = store_dir
 
-        self._buckets = {} # v_id -> Bucket()
         self._leases = set() # should do weakref dances.
 
     def _get_bucket_dir(self, verifierid):
@@ -30,8 +29,7 @@ class BucketStore(service.MultiService, Referenceable):
         bucket_dir = self._get_bucket_dir(verifierid)
         precondition(not os.path.exists(bucket_dir))
         precondition(isinstance(bucket_num, int))
-        bucket = Bucket(bucket_dir, verifierid, bucket_num, size)
-        self._buckets[verifierid] = bucket
+        bucket = WriteBucket(bucket_dir, verifierid, bucket_num, size)
         bucket.set_leaser(leaser_credentials)
         lease = Lease(verifierid, leaser_credentials, bucket)
         self._leases.add(lease)
@@ -39,14 +37,9 @@ class BucketStore(service.MultiService, Referenceable):
 
     def get_bucket(self, verifierid):
         # for now, only returns those created by this process, in this run
-        bucket = self._buckets.get(verifierid)
-        if bucket:
-            precondition(bucket.is_complete())
-            return BucketReader(bucket)
-        elif os.path.exists(self._get_bucket_dir(verifierid)):
-            bucket_dir = self._get_bucket_dir(verifierid)
-            bucket = Bucket(bucket_dir, verifierid, None, None)
-            return BucketReader(bucket)
+        bucket_dir = self._get_bucket_dir(verifierid)
+        if os.path.exists(bucket_dir):
+            return BucketReader(ReadBucket(bucket_dir, verifierid))
         else:
             return NoSuchBucketError()
 
@@ -76,26 +69,10 @@ class BucketReader(Referenceable):
         return self._bucket.read()
 
 class Bucket:
-    def __init__(self, bucket_dir, verifierid, bucket_num, size):
-        if not os.path.isdir(bucket_dir):
-            os.mkdir(bucket_dir)
+    def __init__(self, bucket_dir, verifierid):
         self._bucket_dir = bucket_dir
         self._verifierid = verifierid
 
-        if size is not None:
-            self._size = size
-            self._data = file(os.path.join(self._bucket_dir, 'data'), 'wb')
-            self._bytes_written = 0
-        else:
-            precondition(os.path.exists(os.path.join(self._bucket_dir, 'closed')))
-            self._size = os.path.getsize(os.path.join(self._bucket_dir, 'data'))
-            self._bytes_written = self._size
-
-        if bucket_num is not None:
-            self._write_attr('bucket_num', str(bucket_num))
-        #else:
-            #bucket_num = int(self._read_attr('bucket_num'))
-
     def _write_attr(self, name, val):
         f = file(os.path.join(self._bucket_dir, name), 'wb')
         f.write(val)
@@ -107,10 +84,23 @@ class Bucket:
         f.close()
         return data
 
+    def is_complete(self):
+        return os.path.exists(os.path.join(self._bucket_dir, 'closed'))
+
+class WriteBucket(Bucket):
+    def __init__(self, bucket_dir, verifierid, bucket_num, size):
+        Bucket.__init__(self, bucket_dir, verifierid)
+        precondition(not os.path.exists(bucket_dir))
+        os.mkdir(bucket_dir)
+
+        self._size = size
+        self._data = file(os.path.join(self._bucket_dir, 'data'), 'wb')
+        self._bytes_written = 0
+
+        self._write_attr('bucket_num', str(bucket_num))
+
     def set_leaser(self, leaser):
-        f = file(os.path.join(self._bucket_dir, 'leases'), 'wb')
-        f.write(leaser)
-        f.close()
+        self._write_attr('leases', leaser)
 
     def write(self, data):
         precondition(len(data) + self._bytes_written <= self._size)
@@ -124,15 +114,19 @@ class Bucket:
         self._write_attr('closed', '')
 
     def is_complete(self):
-        return os.path.getsize(os.path.join(self._bucket_dir, 'data')) == self._size
+        complete = Bucket.is_complete(self)
+        if complete:
+            _assert(os.path.getsize(os.path.join(self._bucket_dir, 'data')) == self._size)
+        return complete
+
+class ReadBucket(Bucket):
+    def __init__(self, bucket_dir, verifierid):
+        Bucket.__init__(self, bucket_dir, verifierid)
+        precondition(self.is_complete()) # implicitly asserts bucket_dir exists
 
     def get_bucket_num(self):
         return int(self._read_attr('bucket_num'))
 
     def read(self):
-        precondition(self.is_complete())
-        f = file(os.path.join(self._bucket_dir, 'data'), 'rb')
-        data = f.read()
-        f.close()
-        return data
+        return self._read_attr('data')