Which allows to enable/disable the service, change nodes, keys and other
settings. Unfortunately, atomic.Value doesn't allow Store(nil), so we have to
store a pointer there that can point to nil interface.
Blockchain occupies resources (e.g. it opens log files for DB, etc.)
on creation and running. We need to release these resources if something
goes wrong during execution chain-related commands.
This commit solves the following problem on Windows:
```
--- FAIL: TestServerStart (0.32s)
--- FAIL: TestServerStart/stateroot_service_is_on_&&_StateRootInHeader=true (0.04s)
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestServerStart_stateroot_service_is_on_&&_StateRootInHeader=true460557297\001\neogotestchain\000001.log: The process cannot access the file because it is being used by another process.
--- FAIL: TestServerStart/invalid_Oracle_config (0.03s)
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestServerStart_invalid_Oracle_config810064028\001\neogotestchain\000001.log: The process cannot access the file because it is being used by another process.
--- FAIL: TestServerStart/invalid_consensus_config (0.04s)
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestServerStart_invalid_consensus_config217270091\001\neogotestchain\000001.log: The process cannot access the file because it is being used by another process.
--- FAIL: TestServerStart/invalid_Notary_config (0.07s)
--- FAIL: TestServerStart/invalid_Notary_config/malformed_config (0.04s)
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestServerStart_invalid_Notary_config_malformed_config754934830\001\neogotestchain\000001.log: The process cannot access the file because it is being used by another process.
--- FAIL: TestServerStart/invalid_Notary_config/invalid_wallet (0.03s)
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestServerStart_invalid_Notary_config_invalid_wallet934249397\001\neogotestchain\000001.log: The process cannot access the file because it is being used by another process.
--- FAIL: TestServerStart/good (0.11s)
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestServerStart_good596150160\001\neogotestchain\000001.log: The process cannot access the file because it is being used by another process.
```
This commit also unifies blockchain and services releasing code.
zap never closes open sinks except its own tests. This behaviour
prevents TestHandleLoggingParams from successful cleanup because
temp log output file can't be closed due to the following error:
```
TempDir RemoveAll cleanup: remove C:\\Users\\Anna\\AppData\\Local\\Temp\\TestHandleLoggingParams_debug5796883
33\\001\\file.log: The process cannot access the file because it is being used by another process.
```
So this tremendous cludge is made mosetly for our testing code.
It is not for concurrent usage (we don't have cases of
multithreaded access to logger output sink).
Notice that it makes the node accept Extensible payloads with any category
which is the same way C# node works. We're trusting Extensible senders,
improper payloads are harmless until they DoS the network, but we have some
protections against that too (and spamming with proper category doesn't differ
a lot).
Problem:
```
--- FAIL: TestDumpDB (0.08s)
--- FAIL: TestDumpDB/too_low_chain
testing.go:894: TempDir RemoveAll cleanup: remove C:\Users\Anna\AppData\Local\Temp\TestDumpDB_too_low_chain357310492\001\chains\privnet\000001.log: The process cannot access the file because it is being used by another process.
```
Solution:
Release resources occupied by the chain even on non-error command exit.
1. Initialization is performed via `Blockchain` methods.
2. Native Oracle contract updates list of oracle nodes
and in-fly requests in `PostPersist`.
3. RPC uses Oracle module directly.
If port is dynamically allocated, `(*Server).Addr` will contain
0 port. This commit executes listener before exiting from `Start()`
and sets Addr to the actual address.
It's not needed any more with Go 1.13 as we have wrapping/unwrapping in base
packages. All errors.Wrap calls are replaced with fmt.Errorf, some strings are
improved along the way.
We make it explicit in the appropriate Block/Transaction structures, not via a
singleton as C# node does. I think this approach has a bit more potential and
allows better packages reuse for different purposes.
