Wrap with writer

[wjblanke]

Purpose:

The db_wrapper code allows read operations to use the current write connection if it is active.

Currently the syncing operation uses distinct writes and reads which means write operations are on the writer connection and read operations are on one of the read connections across different threads.

To make life easier for sqlite, this PR wraps block syncs within one db_wrapper writer. The block sync db_wrapper operations then will use the write connection whether it is for reading or writing. The write connection always has an up to date view of the DB.

Current Behavior:

Block sync operations use multiple connections and threads

New Behavior:

Block sync operations use the writer connection

Testing Notes:

This may cause a reduction in concurrency because the db_wrapper write has its own lock. Performance would be the main concern here although with less coherency issues things should be faster.

[coveralls-official]

Pull Request Test Coverage Report for Build 12731382263

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 6 of 6 (100.0%) changed or added relevant lines in 1 file are covered.
• 264 unchanged lines in 12 files lost coverage.
• Overall coverage decreased (-0.03%) to 91.525%

---

Files with Coverage Reduction	New Missed Lines	%
chia/full_node/pending_tx_cache.py	1	96.55%
chia/plotters/plotters.py	1	90.94%
chia/rpc/util.py	2	95.74%
chia/consensus/blockchain.py	2	94.14%
chia/full_node/full_node_api.py	2	84.77%
chia/rpc/rpc_server.py	3	88.24%
chia/server/node_discovery.py	4	80.77%
chia/timelord/timelord_launcher.py	4	89.29%
chia/wallet/wallet_node.py	6	87.96%
chia/plotters/madmax.py	6	44.58%

Totals
Change from base Build 12691593511:	-0.03%
Covered Lines:	105324
Relevant Lines:	114897

---

💛 - Coveralls