try to do deserialization of transaction in a rayon thread

[oxarbitrage]

Motivation

We want to add the deserialization of transactions and blocks in the zebra-network crate into the rayon pool. Resolves #4787

Solution

Implement deserialize transactions and blocks in a rayon thread.

Review

[oxarbitrage]

This code fails compilation with the following:

oxarbitrage@oxarbitrage-Lenovo-ideapad-320S-14IKB:~/zebra/issue4787/zebra$ cargo test
   Compiling zebrad v1.0.0-beta.12 (/home/oxarbitrage/zebra/issue4787/zebra/zebrad)
   Compiling zebra-network v1.0.0-beta.12 (/home/oxarbitrage/zebra/issue4787/zebra/zebra-network)
error[E0597]: `body` does not live long enough
   --> zebra-network/src/protocol/external/codec.rs:413:51
    |
413 |                 let mut body_reader = Cursor::new(&body);
    |                                       ------------^^^^^-
    |                                       |           |
    |                                       |           borrowed value does not live long enough
    |                                       argument requires that `body` is borrowed for `'static`
...
465 |             }
    |             - `body` dropped here while still borrowed

error[E0597]: `body_reader` does not live long enough
   --> zebra-network/src/protocol/external/codec.rs:430:63
    |
430 |                     b"tx\0\0\0\0\0\0\0\0\0\0" => self.read_tx(&mut body_reader),
    |                                                  -------------^^^^^^^^^^^^^^^^-
    |                                                  |            |
    |                                                  |            borrowed value does not live long enough
    |                                                  argument requires that `body_reader` is borrowed for `'static`
...
465 |             }
    |             - `body_reader` dropped here while still borrowed

error[E0502]: cannot borrow `body_reader` as immutable because it is also borrowed as mutable
   --> zebra-network/src/protocol/external/codec.rs:451:22
    |
430 |                     b"tx\0\0\0\0\0\0\0\0\0\0" => self.read_tx(&mut body_reader),
    |                                                  ------------------------------
    |                                                  |            |
    |                                                  |            mutable borrow occurs here
    |                                                  argument requires that `body_reader` is borrowed for `'static`
...
451 |                 .map(|msg| {
    |                      ^^^^^ immutable borrow occurs here
...
455 |                     let extra_bytes = body.len() as u64 - body_reader.position();
    |                                                           ----------- second borrow occurs due to use of `body_reader` in closure

Some errors have detailed explanations: E0502, E0597.
For more information about an error, try `rustc --explain E0502`.
error: could not compile `zebra-network` due to 3 previous errors
warning: build failed, waiting for other jobs to finish...
error: could not compile `zebra-network` due to 3 previous errors
error: could not compile `zebra-network` due to 3 previous errors
oxarbitrage@oxarbitrage-Lenovo-ideapad-320S-14IKB:~/zebra/issue4787/zebra$ 

[teor2345]

I found a way to make it work, I pushed it to this PR in commit 4715696.

Some of the tests will need to be changed to use the multi-threaded tokio runtime, here's an example:

zebra/zebra-network/src/isolated/tor/tests/vectors.rs

Lines 44 to 45 in 9be13a4

	#[tokio::test(flavor = "multi_thread")]
	async fn connect_isolated_run_tor_multi() {

[codecov]

Codecov Report

Merging #4801 (06ed353) into main (81727d7) will increase coverage by 0.07%.
The diff coverage is 57.69%.

@@            Coverage Diff             @@
##             main    #4801      +/-   ##
==========================================
+ Coverage   78.75%   78.83%   +0.07%     
==========================================
  Files         305      305              
  Lines       38066    38109      +43     
==========================================
+ Hits        29980    30044      +64     
+ Misses       8086     8065      -21     

[teor2345]

Thanks, looks good!

[teor2345]

I admin-merged this PR because it is an urgent sync fix.