Diffusion 6.8 Release Notes
6.8.6 (12 August 2022)
Fixes in 6.8.6
29035: Unable to provide session context before session creation
The C Client was unable to receive as a parameter a user context before the session creation. This has now been addressed.
29052: C library dependency clashes
Since v6.8.0, the C client library has internally packaged OpenSSL (and other third party libraries since before v6.8.0). As a result of this, applications have been unable to link their own versions of these libraries as it would result in symbol clashes when linking the application. This issue has now been addressed.
29060: hash_clear not correctly clearing memory allocations
A double free was possible when using the hash_clear function, and then using hash_free on the same HASH_T *. This issue has now been resolved.
29065: missing argument in on_handler_error handler for session_listener
The callback function on_handler_error on the session listener was not being passed the message that caused the error. This issue has now been addressed.
29066: Buffer read functions not protected against NULL pointer
Certain buf_read* functions would throw a Segmentation Fault if passed a NULL pointer. This issue has now been addressed.
29069: Buffer read functions not protected against storing into a NULL argument
Certain buff_read_* functions would cause a memory error when the assignment variable was NULL. This issue has been resolved.
29089: APR symbol renaming
Since v6.8.0, the C client library has internally packaged APR libraries. As a result of this, applications have been unable to link their own versions of these libraries as it would result in symbol clashes when linking the application. This issue has now been addressed.
28548: Remote servers tab does not appear if license contains FANOUT features
If the Diffusion license in use declares FANOUT_SERVER or FANOUT_CLIENT instead of REMOTE_CONNECTIONS the remote servers tab does not appear in the console even though these feature options are logically equivalent.
This has been fixed so that the remote servers tab will appear if any of the named options are present in the license.
29072: Principal cannot be null
Previously, when an empty string or null was passed as the principal when connecting, it was treated as undefined resulting in a connection being attempted without principal AND credentials, even if credentials were explicitly set. Now, an empty string is interpreted as a valid principal and a connection will be attempted with credentials in this case.
29079: Prometheus output contains redundant HELP and TYPE information
Due to a bug in previous releases, the Prometheus HTTP gateway would produce repeated HELP and TYPE lines for each unique combination of dimension labels a metric had. This information was redundant, and caused problems for downstream tools such as New Relic.
The bug has been resolved in this release. Each metric now has a single HELP and TYPE line, regardless of the number of dimensions.
6.8.5 (15 July 2022)
Fixes in 6.8.5
28963: Memory Leak : Persistence compaction retains references to removed topic values after removal
A memory leak in persistence file compaction caused references to removed topic values to be retained. This would lead to increasing heap usage which was especially noticeable when using time series topics. This problem has now been resolved.
6.8.4 (8 July 2022)
Fixes in 6.8.4
28897: Removal of a single replicated topic could silently fail
Due to a bug in previous releases, an API operation to remove a single topic could erroneously report success when topic removal failed due to the cluster repartitioning. The bug has been fixed in this release.
28918: Valid JSON patch can be rejected
Due to a bug in previous releases, the server could incorrectly reject a valid JSON patch. The bug has been fixed in this release.
28940: JSON patch can't be applied to a newly recovered topic
Due to a bug in previous releases, a JSON patch couldn't be applied to topics newly recovered from the cluster or file persistence. Attempting to do so would result fail with a IncompatibleTopicStateException error with a message such as "state FILE cannot have delta applied by APPLICATION".
The bug has been fixed in this release.
6.8.3 (9 June 2022)
Fixes in 6.8.3
28697: OpenSSL Library failure in the C Client for Windows
The C Client for Windows would fail as the openSSL embedded library was still depending externally on an openSSL DLL.
A fully self contained openSSL library is now embedded in the C Client for Windows.
28801: Usage of reserved C++ keyword in C API
The reserved keyword for C++, export, was being used in the C Client public facing API. This has now been fixed.
28837: PersistenceException - Failed to remove REMOVE_TOPIC during compaction
A PersistenceException stating "Failed to remove REMOVE_TOPIC" could occur when compacting persistence files. This led to the compaction stopping, which in turn could lead to disk space filling.
This is likely due to some previous file corruption. The processing has now been changed so that if a remove operation is found for a topic that there is no record of then the compaction will log an error message and proceed.
28651: Server deadlock in DefaultTimeoutSupervisor
In previous releases, a server-side deadlock could occur between the DefaultTimeoutSupervisor thread and a thread from the background thread pool. The only remedy was to restart the server.
The bug has been fixed in this release.
28664: NullpointerException in TopicLoadMessage due to null value provided for reference topic
If a primitive (String, Int64, Double) topic was updated to null (removing its value) and the topic was selected as a source for a topic view, this would cause a NullPointerException to be logged in com.pushtechnology.diffusion.multiplexer.server.subscription.TopicLoadMessage.
This has now been resolved and such an update will now be published to clients as the CBOR null value (hex F6).
28827: NegativeArraySizeException in IBytesOutputStreamImpl
A NegativeArraySizeException in IBytesOutputStreamImpl could occur if a partition was being migrated in a clustered environment and one or more topics within the partition were exceptionally large (most likely time series topics with a large number of events).
The size of data that can be accommodated in the partition log has now been doubled so this is far less likely to happen, however, the partition log size is currently limited by the size of a Java integer.
In the future, the partition log capability will be extended to accommodate such very large values. However, in the meantime, users must be aware that very large values in a single topic could possibly lead to such problems.
28850: NullPointerException in ServerMultiplexerStateImpl when adding topics
Due to a bug in previous releases, an internal subscription index could be corrupted when a session closed. This could cause subscriptions by unrelated sessions to fail, and was apparent from PUSH-000229 or PUSH-000872 messages in the server log. The bug has been fixed in this release.
28771: Correct Prometheus metric name to diffusion_topics_subscriber_update_compressed_bytes
In previous releases, the subscriber_updated_compressed_bytes metric was exported to Prometheus under an incorrect name ("diffusion_topics_subscriber_update_message_bytes"). From this release, the Prometheus metric name has been corrected to "diffusion_subscriber_updated_compressed_bytes".
6.8.2 (28 April 2022)
Fixes in 6.8.2
28647: Newly connecting remote servers can overload the primary server outbound queues
Previously the use of remote topic views could cause a very large number of subscription and initial value notifications to be queued in the primary server outbound queue. If the queue was of an insufficient size to accommodate these notifications the secondary server would be disconnected. The secondary server would then retry the connection causing the same problem to repeat indefinitely.
This problem has now been mitigated by ensuring that the subscription for each distinct remote topic view is executed in series, so each topic view would only start to subscribe when the previous one was complete. This reduces the number of notifications that need to be queued in the primary server at any one time. It is therefore now within the user's control to divide up the subscriptions in remote topic views and thus control the notification rate. It should be noted that any individual remote topic view should still not request a subscription that will request more notifications (up to 2 per topic) than the primary server's outbound queue is able to cope with.
28616: Compaction stopped due to "has invalid timestamp for time series topic" error
In certain circumstances the recovery of persistence files containing time series topics could fail with an error reporting "has invalid timestamp for time series topic" and this in turn could lead to further persistence compaction failures.
This issue has now been resolved.
28539: Failure to update to a topic can be logged twice
In previous releases, a PUSH-000464 message could be logged twice for a topic update failure. The bug has been corrected in this release.
6.8.1 (22 March 2022)
Fixes in 6.8.1
13630: Apple SDK not available via Swift Package Manager
You can now easily add Apple Diffusion SDK to your Xcode solution via Swift Package Manager, available in https://github.com/pushtechnology/diffusion-swift
28368: Cross site scripting vulnerability in the console logs tab
A remote code execution vulnerability in the server logs tab of the Diffusion Management Console has been resolved at this release.
28416: Gateway endpoints tab not visible if no endpoints defined
If a gateway application supported endpoints but none had as yet been defined in the configuration then the endpoints tab was not made visible in the console and so it was not possible to define new endpoints from the console. This has now been resolved.
28351: Correct parameterisation of Diffusion start scripts
Due to a packaging error, enhancements to the start scripts made under case 28366 were not released in 6.8.0. This has been rectified. The server start scripts can be customised using the additional environment variables DIFFUSION_EXT_DIR, LOG4J_CONFIGURATION, JVM_LOG_DIR, and EXTRA_JAVA_PARAMETERS. See the explanatory comments in the scripts for more details.
6.8.0 (28 February 2022)
New features in 6.8.0
27942: Include headers of Kafka records in content of Diffusion topic updates
Headers in Kafka records can now be included in Diffusion updates. In the config, a new config param 'headers' is introduced for 'regexSubscriptions' and 'topicSubscriptions' in publisher. This expects a list of header keys whose values would be looked into in Kafka record and published to Diffusion, together with Key, value and partition details. If "$all" is used a first item in list, all headers will be included.
27365: Journal feature
The new Diffusion journal allows certain 'actions' to be written out to a log file. Actions that are written contain data about what is being performed, along with which principal performed the action. The journal uses Log4J2 allowing the file output to be configured as required.
Please refer to the user manual for more details on how to configure the journal.
27531: Python Core repo with CBOR and Delta bindings
This new package provides Python bindings for native functionality in the Python Client.
1. the CBOR support previously provided by diffusion-cbor
2. Myers-Diff Binary deltas, used for deltas in Diffusion.
At present, we provide binary wheels *only*. We cover all Manylinux platforms, as well as for Python 3.7-3.9 on MacOS (10.14-11.1) and Windows.
Other binaries can be built as required, although the covered platforms should cover the vast majority of use cases.
20654: New 'process' transformation - providing conditionals and calculations
This release introduces a new feature to 'topic views'.
There is now a new 'process' transformation that can be used within a topic view to perform calculations on fields within JSON input and set the results in the output JSON. Conditional processing is also supported, so it is possible to generate reference topics only if certain conditions (based upon the JSON input) are true. Conditions and calculations can be used together, so it is possible to conditionally set fields in the output based upon calculations performed upon the input.
See the SDK documentation or the user manual for full details of how to use the new 'process' transformation.
Improvements in 6.8.0
26071: New SessionEstablishmentTransientException from SessionFactory.open
A new exception called SessionEstablishmentTransientException has been introduced which can be returned from SessionFactory.Open. This exception indicates a transient failure and the client application can reasonably retry the connection.
24656: Changes to Adapter Security Permissions
From this release users will need specific permissions to control adapters (Kafka, CDC, and JMS) and to implement adapters.
A console user that controls adapters will need VIEW_SERVER permissions to view connected adapters and CONTROL_SERVER permissions to manipulate them.
The principal used to implement an adapter will need REGISTER_HANDLER permission.
27588: Include OpenSSL in C Client
OpenSSL is now internally linked in the Diffusion C Client.
26833: Additional environment variables for the Diffusion start scripts
From this release, the server start scripts can be customised using the additional environment variables DIFFUSION_EXT_DIR, LOG4J_CONFIGURATION, JVM_LOG_DIR, and EXTRA_JAVA_PARAMETERS. See the explanatory comments in the scripts for more details.
28021: New subclasses of SessionSecurityException - AuthenticationException and PermissionsException
SessionSecurityException now has subclasses of AuthenticationException and PermissionsException to allow for differentiation between the two possible reasons for the security exception.
28074: Improve memory footprint of cluster partition log compaction
The log compaction process has been tuned, significantly reducing the working memory required to handle a series of large messages sent to a replicated topic.
23364: Topic metric grouping by path segments
A topic metric collector can be configured to partition its results into groups based on topic path. If the new "group by path segments" setting is configured to be a positive number, the metrics will be grouped by path prefix. The setting specifies the number of path segments in the prefix. This avoids the need to create and maintain separate metric collectors for each child path. The setting can be changed using the console or the client API.
In the path a/x, the path segments are "a" and "x". A topic metric collector with the topic selector of ?a// will produce a single set of aggregated metrics for the topics with paths starting a/. If the metric collector is altered to set group by path segments to 2, it will produce separate aggregated metrics for the topic with the path a, for topics with paths starting with a/x, for topics with paths starting a/y, and so on.
See also 27330 for a complementary, separate new setting to limit the number of groups created by a metric collector.
27330: Option to limit the number of groups created by a metric collector
A single metric collector can produce many sets of metrics. For example, a session metric collector can be configured to group by $SessionId, which will create a separate set of metrics for every unique session. Similarly from this release (see 23364), a topic metric collector can group by path segments to create a separate set of metrics for every branch of the topic tree having a unique path prefix with the configured number of segments.
A new "maximum groups" setting has been added to both session and topic metric collectors to place an upper limit on the number of groups created. This provides protection against a metric collector creating an arbitrary number of metric sets, potentially impacting system performance. The setting can be changed using the console or the client API.
27870: New getTopicView method in the TopicViews feature
The TopicViews feature of the Client APIs now has a new getTopicView method allowing a single topic view to be retrieved by name.
Deprecations in 6.8.0
27553: All existing members on enum-like types deprecated
All members on enum-like types have been deprecated. Affected types are CloseReason, ErrorReason, UnsubscribeReason, UpdateFailReason, and TopicAddFailReason
Removals in 6.8.0
27820: Deprecated WhoIs Service has been removed
The deprecated WhoIs service has been removed.
27822: Deprecated store directory removed from PersistenceConfig and Server.xml
The deprecated store-directory item from the persistence element in Server.xsd has been removed along with the corresponding deprecated methods in the PersistenceConfig interface of the server configuration API.
27821: Deprecated Diffusion logging library has been removed
Diffusion uses Log4j2 as its default logging library.
Previous releases included a legacy logging library, which was deprecated in Diffusion 6.4. The legacy library is no longer supported and has been removed from this release.
Fixes in 6.8.0
27630: Disconnection due to "Http fragmentation and extension not supported"
An issue was identified with the .Net client's handling of partial reads. This has now been addressed.
27527: hash_num_new is using minimum slots instead of maximum slots provided as parameter
hash_num_new now correctly uses the maximum number of slots when creating a hash map.
17776: Console shows fractional users connected
The Diffusion management console previously displayed some metrics in graphs with unnecessary decimal places. Graphs consisting only of only integer metrics will no longer have fractional ticks on the Y axis.
27314: Unable to set remote server missing topic notification filter through console
The Diffusion management console did not allow the configuration of a topic notification filter while creating remote servers, functionality which was added to the server in Diffusion 6.7.0. This setting can now be configured through the console user interface.
27371: Topic paths with trailing spaces not handled correctly
In the Diffusion management console, there was no provision made for distinguishing topics whose paths differed in trailing whitespace. Behaviour in such cases has been improved.
27377: Topic view editor discards patch when attempting to edit existing topic view
When using the Diffusion management console to view existing topic views with a JSON patch clause, the console could incorrectly display the topic view without the JSON patch clause. This has been fixed.
27860: Console does not allow connection timeout to be specified
The Diffusion management console did not allow a connection timeout to be specified at login. This option has been added.
27913: Nonsense on license page for commercial license
The Diffusion management console's license page could show some contradictory text when deployed with a commercial license. This has been resolved.
28042: Remote server connection failure to connect stalls multiplexer
A problem with thread locking could cause multiplexers to stall if secondary remote servers fail to connect. This problem has now been resolved.
28180: Inbound threads can be indefinitely blocked by Remote Server API calls
If a remote server connection was blocking for a long time due to other issues then other calls to the remote server feature (create, remove, check, get) could also block inbound threads indefinitely.
This has now been changed so that such calls will time out if unable to proceed due to locks being held by remote server connections.
Java & Android Client
27491: Java examples do not build out of the box
It was not possible to build the Java examples with "mvn package" without first adding a dependency for jackson-annotations. This has now been resolved.
27783: Memory leak in Java client on multiple reconnections
Repeated reconnections from the Java client could cause a memory leak of session related objects in the client VM. This has now been resolved.
24910: Sessions can reconnect even if explicitly closed by another session
An issue has been resolved where the server allowed clients to reconnect during the reconnection timeout, even if they had been explicitly closed by another session. This would only occur if session replication was enabled.
26449: Unresponsive shared session prevents login
When connecting to a shared session, a timeout has been introduced in the case where the SharedWorker is unresponsive
27510: TypeScript definition for RemoteServerBuilder.missingTopicNotificationFilter doesn't allow null parameter
The documentation of RemoteServerBuilder.missingTopicNotificationFilter states that a null parameter can be used to clear the filter. The TypeScript definition didn't allow null to be passed. Now, the type definition has been updated to allow a null parameter.
27859: Connection timeout not configurable
27884: Authenticator throws 'Cannot read properties of null'
When closing an authenticator, it would throw a "REGISTERED_HANDLER_EXCEPTION TypeError: Cannot read properties of null". This has been fixed.
27187: Time series topic creation does not work in Kafka adapter
Fixed a bug where creating timeseries Diffusion topic was not working when publishing to DIffusion from Kafka Topics.
27260: Editing Diffusion topic related detail in Kafka adapter from console does not work
Fixed a bug where updating Diffusion publisher service configuration during runtime prevented updates to be published to updated Diffusion topics.
28159: Persistence restore failure due to file corruption restores no topics
There is the possibility for topic persistence files to become corrupt. The most likely cause of this is some resource issue (memory or disk space) at the time of writing which can lead to a truncated file.
Previously, when restarting a server with such corrupt files the restore would be abandoned, files would be moved to the recovery directory, and the server started with no topics restored.
This fix allows the server to proceed with topics restored so far if a file corruption is detected. The faulty files will still be copied to the recovery directory but the current state already read from files will be written back to the persistence directory as a compacted file.
An error will be logged if this occurs, but as file corruption typically occurs at the end of the persistence files then in most cases this will mean that all topic state at the point of failure, except for the very last write, will be restored successfully.
Files copied to recovery are for diagnostic purposes only and should be manually deleted to save space. However, before deletion, they may be sent to Push Technology support for analysis.
27347: Recursively decode Model-based objects
Fixes an issue where some pydantic.BaseModel-based objects were not being fully decoded from the CBOR. This only affected Session Metrics.
27678: python/client-docs/docs/usage.md embedded code is invalid
Updated API Documentation usage example to reflect breaking changes in the API.
27283: Correct cluster recovery of time-series topics
In previous releases, due to a coding error, re-distributing time series topic data when servers join and leave a cluster did not scale to large numbers of time series events. This could cause protracted instability whenever the cluster topology changed. The problem has been fixed in this release.
27321: "replicated-topics-restored" start condition does not work
Connectors can be configured not to accept connections until a set of conditions is satisfied.
Due to a coding error in previous releases, the "replicated-topics-restored" condition was never triggered. This has been corrected in this release. The condition is satisfied after a server has joined the cluster and received all of the topic data from existing members of the cluster. The server will log a PUSH-000834 INFO message when this happens.
27970: A server joining a stable cluster should not merge topics recovered from file persistence
When servers configured for topic replication first form a cluster, the replicated topics are initialised from the servers persistent files. Each server that forms the initial cluster is responsible for recovering a proportion of the topics. While the cluster continues to run, persistent files are written but not read again.
Due to a bug in previous releases, a server joining a stable cluster could add topics from its persistent files. This bug has been fixed in this release.
27986: Unnecessary assertion from compaction
Due to a bug in previous releases, if the server was run with assertions enabled (-ea), topic replication could fail due to an assertion error during compaction of the persistence log. The bug has been fixed in this release.
28136: Connecting sessions that time out due to Hazelcast blocking never complete and remain in memory and metrics
When running in a cluster connecting sessions could time out if there was never a response from Hazelcast during the connection phase. This led to the session remaining in an unconnected state in the server memory and still showing in session metrics. This problems has now been resolved so that if the Hazelcast interaction does not complete the session closes tidily.
28201: Servers in a cluster are unresponsive when loading a large persistence file
Starting replicated servers in a Diffusion cluster could slow down to such a degree that it would appear that they had completely stalled when restoring from very large persistence files.This was due to unnecessary delta calculations occurring when restoring the cluster.
This has now been resolved.
28266: A server recovering from a persistent file can corrupt a cluster's replicated topic data
Due to a bug in previous releases, a server joining a cluster and recovering topics from a persistent store could corrupt the topic data in the cluster.
This bug had several symptoms, including inconsistencies between the cluster members' topic trees, and internal failures to apply delta updates. (E.g. PUSH-000843 ... state REPLICA cannot have delta applied by REPLICA).
The bug has been fixed in this release.
27968: Setting READ_TOPIC permissions update could fail with an IllegalArgumentException
Due to a bug in previous releases, applying particular combinations of path permission assignments using the security control API could fail with an IllegalArgumentException. The bug has been fixed in this release.
27972: Concurrency issue could lead to a corrupt permissions index
In previous releases, a bug in the code that creates internal index of security permissions could leave the index in a corrupt form. The bug has been fixed in this release.
27976: Upgrade log4j2 to address CVE-2021-44228 security vulnerability
The log4j2 logging library used by Diffusion has been upgraded to version 2.15.0. This addresses a critical security bug [CVS-2021-44228] in log4j2. See https://logging.apache.org/log4j/2.x/security.html for details.
28009: Upgrade log4j2 to address CVE-2021-45046 security vulnerability
The log4j2 logging library used by Diffusion has been upgraded to version 2.17.0. This addresses a critical security bug [CVS-2021-45046] in log4j2. See https://logging.apache.org/log4j/2.x/security.html for details.
28053: Changes to the security configuration fail in a cluster if the security store file is read-only
A bug was introduced in Diffusion 6.6.0 and later releases which corrupted the propagation of security configuration changes across a cluster if the corresponding security store file (SystemAuthentication.store, Security.store) is read-only.
Changing the file permissions so the security store files can be read but not written is supported, and can be useful if a separate mechanism is used to seed security configuration after a cluster is cold-started.
The bug has been fixed in this release. Security store changes are again propagated correctly across the cluster, regardless of whether the security store file is read-only.
27605: Possible leak of sessions (and session metrics) that time out during connection
In certain situations, a client session failing to connect due to a timeout could lead to a memory leak where the server side client object remains. This would also affect metrics as the failed session would remain in the 'open' and 'connected' counts.
This problem has now been resolved.
28247: New subscription inadvertently removed existing subscriptions
Due to a bug in previous releases, the topic selectors maintained by the server for a session could be corrupted by subscription and unsubscription operations. Specifically, the problem could be triggered if a session subscribed to a topic selector with a descendant pattern qualifier ("/", or "//"), for example "?a//", then later redundantly subscribed to a topic selector that is a strict sub-selector of the first one, for example "a/b". The bug could cause another topic selector to be removed in ways that were hard to predict.
The bug has been fixed in this release.
27865: Inserts before patch clauses can cause indeterminate results
It was possible that having an 'insert' clause in a topic view specification before a 'patch' clause could produce indeterminate results and in some situations even lead to orphaned reference topics.
The validation of topic views has now been changed to ensure that any 'insert' clauses happen after 'patch' clauses. A failure will occur when parsing a topic view specification if this is not the case.
28170: JSON patch exception message is misleading
The error message given by an applyJSONPatch operation or a patch operation within a topic view could be misleading. The message would read 'failed on operation  of ' if the second operation failed because it was using the index of the failed operation rather than its number.
This has now been changed so that if the second operation fails then it will read 'failed on operation  of '.
28309: IllegalArgumentException in TopicTreeNodeImpl
A concurrency bug in previous releases could corrupt topics in the topic tree. One side-effect is that a subsequent attempt to add a topic could fail with an IllegalArgumentException. The bug has been fixed in this release.
28449: Reference topics retained by 'preserve topics' are not persisted across server instances or cluster
A new 'preserve topics' clause was introduced to topic views in release 6.6. This clause means that reference topics created by a view (that have a path dependent upon the source topic value) are retained until the source topic is removed or the topic view is removed. Though this is true in the context of a single server instance, it is not the case if the server is restarted as all such topics created during the previous server instance will be lost. It is also not the case if a new server enters a cluster as the new server will only have reference topics generated from the point in time where it joined the cluster and will not reflect reference topics previously created within other cluster peers.
This issue occurs because reference topics are not persisted, either to file or across the cluster.
This issue will be resolved in a future release.