* Extend envoy metric service, scope and OAL lexer/parser.

* Finish metric extension and oal.

* Make test env works.

* Finish test of envoy connection and memory metric.

* Change document.

* Finish docker compose test.

* Add envoy metrics service protos

This patch imports protos from envoyproxy/data-plane-api and
prometheus/client_model to enable metrics service service feature in
SkyWalking OAP.
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add Envoy related docs
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Update the LICENSE to include new protos license

From:
- envoyproxy/data-plane-api
- prometheus/client_model
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add a complete config.yaml example
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add note on Envoy dynamic config
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add protoc-gen-validate license
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Add samples
Signed-off-by: NDhi Aurrahman <dio@tetrate.io>

* Make CI and license right.

* Update README.md

@dhi typo :P

* Update README.md

Another typo :P

* Delete metrics.json

metrics.json is included in identify.json and not be linked in document.

* add serviceInstanceId in Segment storage.

* add serviceInstanceId in query condition.

* Try adjustment.

* Remove heartbeat.

* Make heartbeat back to work. And default threadpool size more sense.

* Make L2 to less than before.

* Make instance heartbeat works.

* Try L1 aggregation thread = core * 2 * 2.

* Correct trace id.

* Fix match.

* Add cover token to retry.

* Retry new test plugin.

* Reset to jacoco.

* Update jacoco version.

[Performance Improvement]Backend streaming thread model improvement

* The prototype of topN sql worker.

* Add scope and new manual dispatcher.

* no message

* Finish topN persistence codes. Not test yet. And query have not added.

* Finish the top n database statement persistent.

* Support different slow thresholds for different db types.

* Fix wrong db default threshold

* Finish new query protocol binding.

* Provide query empty implementation and sync ui.

* Finish all codes, hope it works :P
I will run the tests tonight.

* Fix

* Fix

* Fix a startup issue.

* Add time bucket to persistent.

* Fix wrong query result column name.

* Fix Database query.

* Fix checkstyle.

* Fix wrong order logic, and add a test case to verify, to fix https://github.com/apache/incubator-skywalking/pull/2239#discussion_r255948249

* Add Database source

* Add DatabaseSource source and database_* script for oal

* Enable Database_Indicator

* Add file license

* Rename DatabaseService to ClientDatabase. In the future, we may have real database server monitoring.

* Add query database from H2

* refactor

* update submodule

* refactor

* Fix style

* Fix: unknown tag error

* fix checkstyle

for issue#2196

* 1. Sleep 500 milliseconds after a batch re-call finish.
2. Re-create register lock index when the system property named debug is setting.
3. Get the register inventory before lock to avoid increment the sequence but not use.
4. Return the exchange flag after all the references and spans in one segment parsed to reduce the number of segment parse.
5. Put the not exchanged segment into a collection then try to exchange no more than 10 times because of the exchange is asynchronous.
6. Cache the segment object to avoid repeated deserialization.

#2185

* #2185
1. Sleep 500 milliseconds after a batch re-call finish.
2. Re-create register lock index when the system property named debug is setting.
3. Get the register inventory before lock to avoid increment the sequence but not use.

* #2183

Merge commit into master.

* Make the h2 register lock same as mysql.

* [maven-release-plugin] prepare release v6.0.0-GA

* [maven-release-plugin] prepare for next development iteration

* Update ReferenceIdExchanger.java

Change comments of codes.

* Refactor service instance inventory to properties based entity.

* Fix a bug and refactor properties update.

* Add properties for service inventory

* Fix code bugs

* Provide develop doc for inventory extension.

* Change a label name for  sw instance to avoid confict.

* Fix a wrong metric name.

* Fix too many counter instances.

* Set uptime to second.

* Fix format.

* Fix format

* Remove two unnecessary counter.

* Provide grafana dashboard settings and remove unnecessary metric.

* Provide a simple UI brief doc. Fix #2137

* Finish the basic codes of telemetry.

* Add many telemetry in oap.

* Fix a test case.

* Finish all telemetry metric.

* Fix format.

* Make telemetry works.

* Support JVM metrics.

* Add doc for telemetry.

* Fix typo.

* Fix #2135

* Change srcLayer to nodeType. Add nodeType in service inventory entity.

* NodeType value refactor.

* Format codes.

* Fix compile issue.

* Fix bugs, and make query on service inventory instead of network inventory

osName and hostName values are reversed。

* Provide consul cluster plugin.

* Change log and application config file.

* Add consul's config item into the docker's application.yml.

* Fixed bug.

* Add consul description into  readme.

* Add okhttp component license.

* Update submodule skywalking-ui

* Fix #1925 Add namespace to service name

* Support sampling trace at server side and keep metric right.

* Add a trace sampling document

* Fix wrong default value.

* Fix document issue.

* Fix assemble issue.

* Fix wrong settings and doc.

Also fixed several bugs in this merge.

2. Close the input stream when switch to read next file.

#1665

* Close the clients which are unreachable.
Remote client manager test case and comments.

* Test the GRPCRemote client.

* 1. Catch the throwable for onComplete method cause of it will throw exception when connection lost.
2. Check the gRPC channel state, send message when state is ready, wait 5 second when state is not ready.

Notice: gRPC channel getState with true parameter will trigger reconnect operation.

* gRPC client will reconnect to the server when network recorvered.

* Recovery application.yml

* Recovery proto module commit id.

* no message

* Fixed compile error.

* Update new protocol

* Support new protocol at agent side.

* Fix test case.

* Make backend supports new trace protocol

* Fix tests.

* Make all new services available in gRPC.

* Fix bugs.

* Finish new document for v2 trace protocol.

* Fix wrong version requirement of zk

* Fix trace query bug.

* Find a client side dictionary bug.

* Fix register bugs.

* Fix break doc links.

Fixed a bug which the segment record index does not delete the history data because of the saving time bucket is a second format date, but the query delete is minute format date. (#1943)

#1942

* Change some codes to make zipkin receiver works, not done yet.

* @adriancole Zipkin receiver is coming back again.

* Fix document and fix for Zipkin receiver.

* Fix some bugs.

* Fix register bug.

* Fix transfer bug for new backend core.

* OAP server testing module.

#1930

* #Missing delete code.

* Add some supports to sw6 header. Break many test cases because I turn sw3 default off. For sure, you could open in agent.conf.  FYI @peng-yongsheng @ascrutae

* Fix CI and make user cases still work under v1 header.

* Support BASE64 in v2 header and make entryOperationName and parentOperationName optional in ContextCarrier or ContextSnapshot

* Fix CI.

* @peng-yongsheng This is backend related, please pay attention.

* Fix the carrier item order is incorrect (#1903)

* Lock oracle and resin plugins version.

* Move resin and oracle plugin to openskywalking

* Restore submodule active.

* Add another submodule active command.

* Remove the wrong test cases in release and fix some doc issues.

* [maven-release-plugin] prepare release v6.0.0-alpha

* [maven-release-plugin] prepare for next development iteration

* Fix some doc

* Fix mesh receiver doesn't update heartbeat.

* Fix bug of mesh heartbeat and rest receiver.

* Fix issue: opencensus is included in agent without shade. @tuohai666