Remove cond_var in verification_complete at startup

[HaoranYi]

Problem

WaitableCondVar in VerifyAccountsHashInBackground struct at startup is no longer needed. We no longer block the main thread during hash verification. And the only call on the cond_var is wait_for_timeout with duration of zero, which doesn't block at all. And this wait is unnecessary, since we can know if the background process has completed from another atomic variable 'background_completed`.

Summary of Changes

Remove cond_var in VerifyAccountsHashInBackground

Fixes #

[jeffwashington]

lgtm

[brooksprumo]

I think the one nice thing about the condition variable is the notify/wakeup on completion. Since the validator is only really checking/blocking for completion in one place, and it is in the background, we're not really in need of this feature though. So I'm fine with removing the condition variable here.

[HaoranYi]

I think the one nice thing about the condition variable is the notify/wakeup on completion. Since the validator is only really checking/blocking for completion in one place, and it is in the background, we're not really in need of this feature though. So I'm fine with removing the condition variable here.

This code is called in replay stage

agave/core/src/replay_stage.rs

Line 2124 in a0b2c73

if !parent.is_startup_verification_complete() {

.

It may not make much difference. But removing the cond_var may help to save a few instructions for replaying at startup.