Refactoring to better support new protocol versions #400
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It encapsulates all the logic related to the Bolt protocol negotiation and versioned packstream components.
Connection is now less coupled with protocol messages. It is able to write an arbitrary `RequestMessage` instead of exposing functions to write messages of a specific type, like `Connection#pullAll()`. Also introduced a `BoltProtocol` abstraction which exposes only logical operations, like "initialize the connection" or "run a query". It should make it simpler to introduce new protocol version that uses different messages to execute same logical operations.
Make it expose logical operations for explicit transactions like begin, commit and rollback. These operations require different set of messages in Bolt V3. Having operations exposed like this should make it easier to override them.
Moved creation of `Packer` and `Unpacker` into `BoltProtocol` because they are in lockstep with each other. This makes protocol handshaker simpler because it only needs to do a single version check. Introduced a class that represents Bolt V2 with different packing and unpacking capabilities.
Add a configuration option to the neo4j.conf file to speed-up some tests. New value is 5 seconds instead of default 30 seconds.
Routing driver removes address from the routing table on error. This removal is triggered by a `StreamObserver` that observes the incoming messages. Same observer is used for RUN and PULL_ALL. It used to trigger the forget operation trice on every error. This wasn't harmful but looked weird in logs. This commit fixes the problem by making `StreamObserver` invoke the provided callback only once.
ali-ince
approved these changes
Aug 23, 2018
| * @return {BoltProtocol} bolt protocol corresponding to the version suggested by the database. | ||
| * @throws {Neo4jError} when bolt protocol can't be instantiated. | ||
| */ | ||
| readHandshakeResponse(buffer) { |
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Would it be better to name this to something like createNegotiatedProtocol? Wdyt?
| * @throws {Neo4jError} when bolt protocol can't be instantiated. | ||
| */ | ||
| readHandshakeResponse(buffer) { | ||
| const proposedVersion = buffer.readInt32(); |
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and this maybe to negotiatedVersion?
src/v1/transaction.js
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| // for commit & rollback we need result that uses real connection holder and notifies it when | ||
| // connection is not needed and can be safely released to the pool | ||
| return new Result(observer, msg, {}, emptyMetadataSupplier, connectionHolder); | ||
| return new Result(observer, '', {}, emptyMetadataSupplier, connectionHolder); |
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Does it make sense to use something other than '' here - just for clarity?
* Use new query parameter syntax `$param` instead of deprecated `{param}`
* Do not use ES6 dynamic object key syntax
* improve naming of functions and variables in `ProtocolHandshaker` * preserve statement for commit and rollback results for backwards compatibility
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RequestMessageinstead of exposing functions to write messages of a specific type, likeConnection#pullAll(). Also introduced aBoltProtocolabstraction which exposes only logical operations, like "initialize the connection" or "run a query". It should make it simpler to introduce new protocol version that uses different messages to execute same logical operations.