Provide 500ms for speculative blocks

[heifner]

Since AntelopeIO/leap#1481 speculative blocks honor block deadlines so that "Start speculative blocks every block interval but not more often". However, since 50ms threshold was use it could set a deadline that would be hit before another block came causing a needless restart of a transaction and restart of a block.

For example:

info  2024-08-12T15:18:22.511 nodeos    controller.cpp:3525           log_applied          ] Received block ebede3ba155c0f61... #2154995 @ 2024-08-12T15:18:22.500 signed by lioninjungle [trxs: 2, lib: 2154993, net: 432, cpu: 351, elapsed: 619, time: 1966, latency: 11 ms]
debug 2024-08-12T15:18:22.511 nodeos    producer_plugin.cpp:2005      start_block          ] Starting block #2154996 2024-08-12T15:18:23.000 producer lioninjungle
debug 2024-08-12T15:18:22.511 nodeos    producer_plugin.cpp:2162      remove_expired_trxs  ] Processed 0 expired transactions of the 1 transactions in the unapplied queue.
debug 2024-08-12T15:18:22.511 nodeos    producer_plugin.cpp:2643      schedule_production_ ] Speculative Block Created; Scheduling Speculative/Production Change
debug 2024-08-12T15:18:22.511 nodeos    producer_plugin.cpp:2699      schedule_delayed_pro ] Scheduling Speculative/Production Change at 2024-08-12T15:18:47.500
debug 2024-08-12T15:18:22.685 nodeos    producer_plugin.cpp:869       restart_speculative_ ] Restarting exhausted speculative block #2154996
debug 2024-08-12T15:18:22.685 nodeos    producer_plugin.cpp:309       report               ] Block #2154996 lioninjungle trx idle: 173057us out of 173987us, success: 0, 0us, fail: 0, 0us, transient: 0, 0us, other: 930us
debug 2024-08-12T15:18:22.685 nodeos    producer_plugin.cpp:2005      start_block          ] Starting block #2154996 2024-08-12T15:18:23.000 producer lioninjungle
debug 2024-08-12T15:18:22.685 nodeos    producer_plugin.cpp:2162      remove_expired_trxs  ] Processed 0 expired transactions of the 2 transactions in the unapplied queue.
debug 2024-08-12T15:18:22.685 nodeos    producer_plugin.cpp:2553      process_incoming_trx ] Processing 1 pending transactions
debug 2024-08-12T15:18:22.685 nodeos    producer_plugin.cpp:2579      process_incoming_trx ] Processed 1 pending transactions, 0 left
debug 2024-08-12T15:18:22.685 nodeos    producer_plugin.cpp:2643      schedule_production_ ] Speculative Block Created; Scheduling Speculative/Production Change
debug 2024-08-12T15:18:22.685 nodeos    producer_plugin.cpp:2699      schedule_delayed_pro ] Scheduling Speculative/Production Change at 2024-08-12T15:18:47.500
debug 2024-08-12T15:18:22.971 nodeos    producer_plugin.cpp:783       on_incoming_block    ] received incoming block 2154996 0020e1f42cb0c29fb64575c9b3ed4a4135a43180eab3a0a950aa15c3bf189567
debug 2024-08-12T15:18:22.971 nodeos    producer_plugin.cpp:309       report               ] Block #2154996 lioninjungle trx idle: 284523us out of 286360us, success: 3, 1161us, fail: 0, 0us, transient: 0, 0us, other: 676us
debug 2024-08-12T15:18:22.973 nodeos    producer_plugin.cpp:666       on_block             ] Removed applied transactions before: 3, after: 1
info  2024-08-12T15:18:22.973 nodeos    controller.cpp:3525           log_applied          ] Received block 2cb0c29fb64575c9... #2154996 @ 2024-08-12T15:18:23.000 signed by lioninjungle [trxs: 2, lib: 2154994, net: 432, cpu: 251, elapsed: 641, time: 2026, latency: -26 ms]

Instead give a speculative block a full block interval (500ms) before considering it exhausted.

[ericpassmore]

Note:start
group: STABILITY
category: INTERNALS
summary: Provide 500ms for speculative blocks.
Note:end