This change adds adds an ability to use different source of time for whisper:
when envelope is created it is used to set expiry
to track when envelope needs to be expired
This time is then used to check validity of the envelope when it is received. Currently If we receive an envelope that is sent from future - peer will get disconnected. If envelope that was received has an expiry less then now it will be simply dropped, if expiry is less than now + 10*2 seconds peer will get dropped.
So, it is clear that whisper depends on time. And any time we get a skew with peers that is > 20s reliability will be grealy reduced.
In this change another source of time for whisper will be used. This time source will use ntp servers from pool.ntp.org to compute offset. When whisper queries time - this offset will be added/substracted from current time.
Query is executed every 2 mins, queries 5 different servers, cut offs min and max and the computes mean value. pool.ntp.org is resolved to different servers and according to documentation you will rarely hit the same.
Closes: #687
* Add default peer limits configuration
If discovery is enabled for a given cluster - we will set a default
expected number of peers for each enabled service. For example:
- if cluster is rinkeby has a discovery enabled we will
check which services are enabled
- if whisper is enabled we will set min and max limits by default
- if les is enabled and infura is not used we will set limits too
When statusd is used - configuration must be provided using configuration
supported by statusd.
* Fix deadlock in les peer set
This change will greatly simplify writing unit tests when a node is required but data persistence is irrelevant.
I also Introduced some refactoring and unit tests for `StatusNode`.
- [x] [#797] : Remove unused methods PopulateStaticPeers, ReconnectStaticPeers, removeStaticPeers, removePeer
- [x] [#797] : Rename node.Manager to node. StatusNode and simplify its public api
- [x] [#797] : Rename all references to nodeManager to statusNode
