Use less memory when putting docs on couch. Closes #5011.

4 files changed, 199 insertions, 141 deletions

diff --git a/common/changes/feature_5011-use-less-memory-when-putting-docs-on-couch b/common/changes/feature_5011-use-less-memory-when-putting-docs-on-couch
new file mode 100644
index 00000000..7d3f6e4f
--- /dev/null
+++ b/common/changes/feature_5011-use-less-memory-when-putting-docs-on-couch
@@ -0,0 +1 @@
+  o Use less memory when putting docs on couch (#5011).
diff --git a/common/src/leap/soledad/common/couch.py b/common/src/leap/soledad/common/couch.py
index 40d64370..09fe1ca3 100644
--- a/common/src/leap/soledad/common/couch.py
+++ b/common/src/leap/soledad/common/couch.py
@@ -24,10 +24,21 @@ import uuid
 import logging
 import binascii
 import socket
+import time
+import sys
+
+
+from StringIO import StringIO
 
 
 from couchdb.client import Server
-from couchdb.http import ResourceNotFound, Unauthorized, ServerError, Session
+from couchdb.http import (
+    ResourceConflict,
+    ResourceNotFound,
+    Unauthorized,
+    ServerError,
+    Session,
+)
 from u1db import query_parser, vectorclock
 from u1db.errors import (
     DatabaseDoesNotExist,
@@ -87,9 +98,9 @@ class CouchDocument(SoledadDocument):
         SoledadDocument.__init__(self, doc_id, rev, json, has_conflicts)
         self._couch_rev = None
         self._conflicts = None
-        self._modified_conflicts = False
+        self._transactions = None
 
-    def ensure_fetch_conflicts(self, get_conflicts_fun):
+    def _ensure_fetch_conflicts(self, get_conflicts_fun):
         """
         Ensure conflict data has been fetched from the server.
 
@@ -120,8 +131,7 @@ class CouchDocument(SoledadDocument):
         :type doc: CouchDocument
         """
         if self._conflicts is None:
-            raise Exception("Run self.ensure_fetch_conflicts first!")
-        self._modified_conflicts = True
+            raise Exception("Run self._ensure_fetch_conflicts first!")
         self._conflicts.append(doc)
         self.has_conflicts = len(self._conflicts) > 0
 
@@ -133,25 +143,13 @@ class CouchDocument(SoledadDocument):
         :type conflict_revs: [str]
         """
         if self._conflicts is None:
-            raise Exception("Run self.ensure_fetch_conflicts first!")
+            raise Exception("Run self._ensure_fetch_conflicts first!")
         conflicts_len = len(self._conflicts)
         self._conflicts = filter(
             lambda doc: doc.rev not in conflict_revs,
             self._conflicts)
-        if len(self._conflicts) < conflicts_len:
-            self._modified_conflicts = True
         self.has_conflicts = len(self._conflicts) > 0
 
-    def modified_conflicts(self):
-        """
-        Return whether this document's conflicts have been modified.
-
-        :return: Whether this document's conflicts have been modified.
-        :rtype: bool
-        """
-        return self._conflicts is not None and \
-            self._modified_conflicts is True
-
     def _get_couch_rev(self):
         return self._couch_rev
 
@@ -160,6 +158,14 @@ class CouchDocument(SoledadDocument):
 
     couch_rev = property(_get_couch_rev, _set_couch_rev)
 
+    def _get_transactions(self):
+        return self._transactions
+
+    def _set_transactions(self, rev):
+        self._transactions = rev
+
+    transactions = property(_get_transactions, _set_transactions)
+
 
 # monkey-patch the u1db http app to use CouchDocument
 http_app.Document = CouchDocument
@@ -225,6 +231,94 @@ def raise_server_error(exc, ddoc_path):
     raise errors.DesignDocUnknownError(path)
 
 
+class MultipartWriter(object):
+    """
+    A multipart writer adapted from python-couchdb's one so we can PUT
+    documents using couch's multipart PUT.
+
+    This stripped down version does not allow for nested structures, and
+    contains only the essential things we need to PUT SoledadDocuments to the
+    couch backend.
+    """
+
+    CRLF = '\r\n'
+
+    def __init__(self, fileobj, headers=None, boundary=None):
+        """
+        Initialize the multipart writer.
+        """
+        self.fileobj = fileobj
+        if boundary is None:
+            boundary = self._make_boundary()
+        self._boundary = boundary
+        self._build_headers('related', headers)
+
+    def add(self, mimetype, content, headers={}):
+        """
+        Add a part to the multipart stream.
+        """
+        self.fileobj.write('--')
+        self.fileobj.write(self._boundary)
+        self.fileobj.write(self.CRLF)
+        headers['Content-Type'] = mimetype
+        self._write_headers(headers)
+        if content:
+            # XXX: throw an exception if a boundary appears in the content??
+            self.fileobj.write(content)
+            self.fileobj.write(self.CRLF)
+
+    def close(self):
+        """
+        Close the multipart stream.
+        """
+        self.fileobj.write('--')
+        self.fileobj.write(self._boundary)
+        # be careful not to have anything after '--', otherwise old couch
+        # versions (including bigcouch) will fail.
+        self.fileobj.write('--')
+
+    def _make_boundary(self):
+        """
+        Create a boundary to discern multi parts.
+        """
+        try:
+            from uuid import uuid4
+            return '==' + uuid4().hex + '=='
+        except ImportError:
+            from random import randrange
+            token = randrange(sys.maxint)
+            format = '%%0%dd' % len(repr(sys.maxint - 1))
+            return '===============' + (format % token) + '=='
+
+    def _write_headers(self, headers):
+        """
+        Write a part header in the buffer stream.
+        """
+        if headers:
+            for name in sorted(headers.keys()):
+                value = headers[name]
+                self.fileobj.write(name)
+                self.fileobj.write(': ')
+                self.fileobj.write(value)
+                self.fileobj.write(self.CRLF)
+        self.fileobj.write(self.CRLF)
+
+    def _build_headers(self, subtype, headers):
+        """
+        Build the main headers of the multipart stream.
+
+        This is here so we can send headers separete from content using
+        python-couchdb API.
+        """
+        self.headers = {}
+        self.headers['Content-Type'] = 'multipart/%s; boundary="%s"' % \
+                                       (subtype, self._boundary)
+        if headers:
+            for name in sorted(headers.keys()):
+                value = headers[name]
+                self.headers[name] = value
+
+
 class CouchDatabase(CommonBackend):
     """
     A U1DB implementation that uses CouchDB as its persistence layer.
@@ -564,8 +658,12 @@ class CouchDatabase(CommonBackend):
                 and '_attachments' in result \
                 and 'u1db_conflicts' in result['_attachments']:
             doc.has_conflicts = True
+            #doc.conflicts = self._build_conflicts(
+            #    json.loads(result['_attachments']['u1db_conflicts']))
         # store couch revision
         doc.couch_rev = result['_rev']
+        # store transactions
+        doc.transactions = result['u1db_transactions']
         return doc
 
     def get_doc(self, doc_id, include_deleted=False):
@@ -616,6 +714,10 @@ class CouchDatabase(CommonBackend):
         """
         Put the document in the Couch backend database.
 
+        Note that C{old_doc} must have been fetched with the parameter
+        C{check_for_conflicts} equal to True, so we can properly update the
+        new document using the conflict information from the old one.
+
         :param old_doc: The old document version.
         :type old_doc: CouchDocument
         :param doc: The document to be put.
@@ -637,45 +739,61 @@ class CouchDatabase(CommonBackend):
                                              design document for an yet
                                              unknown reason.
         """
-        trans_id = self._allocate_transaction_id()
-        # encode content
-        content = doc.get_json()
-        if content is not None:
-            content = binascii.b2a_base64(content)[:-1]  # exclude trailing \n
-        # encode conflicts
-        conflicts = None
-        update_conflicts = doc.modified_conflicts()
-        if update_conflicts is True:
-            if doc.has_conflicts:
-                conflicts = binascii.b2a_base64(
-                    json.dumps(
-                        map(lambda cdoc: (cdoc.rev, cdoc.content),
-                            doc.get_conflicts()))
-            )[:-1]  # exclude \n
-        # perform the request
-        ddoc_path = ['_design', 'docs', '_update', 'put', doc.doc_id]
-        resource = self._database.resource(*ddoc_path)
+        attachments = {}  # we save content and conflicts as attachments
+        parts = []  # and we put it using couch's multipart PUT
+        # save content as attachment
+        if doc.is_tombstone() is False:
+            content = doc.get_json()
+            attachments['u1db_content'] = {
+                'follows': True,
+                'content_type': 'application/octet-stream',
+                'length': len(content),
+            }
+            parts.append(content)
+        # save conflicts as attachment
+        if doc.has_conflicts is True:
+            conflicts = json.dumps(
+                map(lambda cdoc: (cdoc.rev, cdoc.content),
+                    doc.get_conflicts()))
+            attachments['u1db_conflicts'] = {
+                'follows': True,
+                'content_type': 'application/octet-stream',
+                'length': len(conflicts),
+            }
+            parts.append(conflicts)
+        # store old transactions, if any
+        transactions = old_doc.transactions[:] if old_doc is not None else []
+        # create a new transaction id and timestamp it so the transaction log
+        # is consistent when querying the database.
+        transactions.append(
+            # here we store milliseconds to keep consistent with javascript
+            # Date.prototype.getTime() which was used before inside a couchdb
+            # update handler.
+            (int(time.time() * 1000),
+            self._allocate_transaction_id()))
+        # build the couch document
+        couch_doc = {
+            '_id': doc.doc_id,
+            'u1db_rev': doc.rev,
+            'u1db_transactions': transactions,
+            '_attachments': attachments,
+        }
+        # if we are updating a doc we have to add the couch doc revision
+        if old_doc is not None:
+            couch_doc['_rev'] = old_doc.couch_rev
+        # prepare the multipart PUT
+        buf = StringIO()
+        envelope = MultipartWriter(buf)
+        envelope.add('application/json', json.dumps(couch_doc))
+        for part in parts:
+            envelope.add('application/octet-stream', part)
+        envelope.close()
+        # try to save and fail if there's a revision conflict
         try:
-            response = resource.put_json(
-                body={
-                    'couch_rev': old_doc.couch_rev
-                        if old_doc is not None else None,
-                    'u1db_rev': doc.rev,
-                    'content': content,
-                    'trans_id': trans_id,
-                    'conflicts': conflicts,
-                    'update_conflicts': update_conflicts,
-                },
-                headers={'content-type': 'application/json'})
-            # the document might have been updated in between, so we check for
-            # the return message
-            msg = response[2].read()
-            if msg == 'ok':
-                return
-            elif msg == 'revision conflict':
-                raise RevisionConflict()
-        except ResourceNotFound as e:
-            raise_missing_design_doc_error(e, ddoc_path)
+            self._database.resource.put_json(
+                doc.doc_id, body=buf.getvalue(), headers=envelope.headers)
+        except ResourceConflict:
+            raise RevisionConflict()
 
     def put_doc(self, doc):
         """
@@ -810,6 +928,25 @@ class CouchDatabase(CommonBackend):
         self._put_doc(old_doc, doc)
         return new_rev
 
+    def _build_conflicts(self, doc_id, attached_conflicts):
+        """
+        Build the conflicted documents list from the conflicts attachment
+        fetched from a couch document.
+
+        :param attached_conflicts: The document's conflicts as fetched from a
+                                   couch document attachment.
+        :type attached_conflicts: dict
+        """
+        conflicts = []
+        for doc_rev, content in attached_conflicts:
+            doc = self._factory(doc_id, doc_rev)
+            if content is None:
+                doc.make_tombstone()
+            else:
+                doc.content = content
+            conflicts.append(doc)
+        return conflicts
+
     def _get_conflicts(self, doc_id, couch_rev=None):
         """
         Get the conflicted versions of a document.
@@ -830,16 +967,8 @@ class CouchDatabase(CommonBackend):
         resource = self._database.resource(doc_id, 'u1db_conflicts')
         try:
             response = resource.get_json(**params)
-            conflicts = []
-            # build the conflicted versions
-            for doc_rev, content in json.loads(response[2].read()):
-                doc = self._factory(doc_id, doc_rev)
-                if content is None:
-                    doc.make_tombstone()
-                else:
-                    doc.content = content
-                conflicts.append(doc)
-            return conflicts
+            return self._build_conflicts(
+                doc_id, json.loads(response[2].read()))
         except ResourceNotFound:
             return []
 
@@ -970,7 +1099,7 @@ class CouchDatabase(CommonBackend):
                            serialized string.
         :type my_content: str
         """
-        doc.ensure_fetch_conflicts(self._get_conflicts)
+        doc._ensure_fetch_conflicts(self._get_conflicts)
         doc.add_conflict(
             self._factory(doc_id=doc.doc_id, rev=my_doc_rev,
                           json=my_content))
@@ -988,7 +1117,7 @@ class CouchDatabase(CommonBackend):
         :param conflict_revs: A list of the revisions to be deleted.
         :param conflict_revs: [str]
         """
-        doc.ensure_fetch_conflicts(self._get_conflicts)
+        doc._ensure_fetch_conflicts(self._get_conflicts)
         doc.delete_conflicts(conflict_revs)
 
     def _prune_conflicts(self, doc, doc_vcr):
@@ -1150,7 +1279,7 @@ class CouchDatabase(CommonBackend):
         if cur_doc is not None:
             doc.couch_rev = cur_doc.couch_rev
         # fetch conflicts because we will eventually manipulate them
-        doc.ensure_fetch_conflicts(self._get_conflicts)
+        doc._ensure_fetch_conflicts(self._get_conflicts)
         # from now on, it works just like u1db sqlite backend
         doc_vcr = vectorclock.VectorClockRev(doc.rev)
         if cur_doc is None:
diff --git a/common/src/leap/soledad/common/ddocs/docs/updates/put.js b/common/src/leap/soledad/common/ddocs/docs/updates/put.js
deleted file mode 100644
index 5a4647de..00000000
--- a/common/src/leap/soledad/common/ddocs/docs/updates/put.js
+++ /dev/null
@@ -1,64 +0,0 @@
-function(doc, req){
-    /* we expect to receive the following in `req.body`:
-     * {
-     *     'couch_rev': '<couch_rev>',
-     *     'u1db_rev': '<u1db_rev>',
-     *     'content': '<base64 encoded content>',
-     *     'trans_id': '<reansaction_id>'
-     *     'conflicts': '<base64 encoded conflicts>',
-     *     'update_conflicts': <boolean>
-     * }
-     */
-    var body = JSON.parse(req.body);
-
-    // create a new document document
-    if (!doc) {
-        doc = {}
-        doc['_id'] = req['id'];
-    }
-    // or fail if couch revisions do not match
-    else if (doc['_rev'] != body['couch_rev']) {
-        // of fail if revisions do not match
-        return [null, 'revision conflict']
-    }
-
-    // store u1db rev
-    doc.u1db_rev = body['u1db_rev'];
-
-    // save content as attachment
-    if (body['content'] != null) {
-        // save u1db content as attachment
-        if (!doc._attachments)
-            doc._attachments = {};
-        doc._attachments.u1db_content =  {
-            content_type: "application/octet-stream",
-            data: body['content']  // should be base64 encoded
-        };
-    }
-    // or delete the attachment if document is tombstone
-    else if (doc._attachments &&
-             doc._attachments.u1db_content)
-        delete doc._attachments.u1db_content;
-
-    // store the transaction id
-    if (!doc.u1db_transactions)
-        doc.u1db_transactions = [];
-    var d = new Date();
-    doc.u1db_transactions.push([d.getTime(), body['trans_id']]);
-
-    // save conflicts as attachment if they were sent
-    if (body['update_conflicts'])
-        if (body['conflicts'] != null) {
-            if (!doc._attachments)
-                doc._attachments = {};
-            doc._attachments.u1db_conflicts = {
-                content_type: "application/octet-stream",
-                data: body['conflicts']  // should be base64 encoded
-            }
-        } else {
-            if(doc._attachments && doc._attachments.u1db_conflicts)
-                delete doc._attachments.u1db_conflicts
-        }
-
-    return [doc, 'ok'];
-}
diff --git a/common/src/leap/soledad/common/tests/test_couch.py b/common/src/leap/soledad/common/tests/test_couch.py
index dc0ea906..97d744e4 100644
--- a/common/src/leap/soledad/common/tests/test_couch.py
+++ b/common/src/leap/soledad/common/tests/test_couch.py
@@ -495,10 +495,6 @@ class CouchDatabaseExceptionsTests(CouchDBTestCase):
         self.assertRaises(
             errors.MissingDesignDocError,
             self.db._get_transaction_log)
-        # create_doc()
-        self.assertRaises(
-            errors.MissingDesignDocError,
-            self.db.create_doc, {})
         # whats_changed()
         self.assertRaises(
             errors.MissingDesignDocError,
@@ -645,10 +641,6 @@ class CouchDatabaseExceptionsTests(CouchDBTestCase):
         self.assertRaises(
             errors.MissingDesignDocDeletedError,
             self.db._get_transaction_log)
-        # create_doc()
-        self.assertRaises(
-            errors.MissingDesignDocDeletedError,
-            self.db.create_doc, {})
         # whats_changed()
         self.assertRaises(
             errors.MissingDesignDocDeletedError,