Allow not waiting for block download before sync (#888)

Fix #410

internal/config_specification.toml

@@ -105,6 +105,10 @@ doc = "Disable Electrum RPC server - only sync and index blocks."
 name = "sync_once"
 doc = "Exit after the initial sync is over (don't start Electrum server)."
 
+[[switch]]
+name = "skip_block_download_wait"
+doc = "Don't wait for block download to finish before starting sync."
+
 [[switch]]
 name = "version"
 doc = "Print out the program version."

src/config.rs

@@ -140,6 +140,7 @@ pub struct Config {
     pub auto_reindex: bool,
     pub ignore_mempool: bool,
     pub sync_once: bool,
+    pub skip_block_download_wait: bool,
     pub disable_electrum_rpc: bool,
     pub server_banner: String,
     pub signet_magic: Magic,
@@ -346,6 +347,7 @@ impl Config {
             auto_reindex: config.auto_reindex,
             ignore_mempool: config.ignore_mempool,
             sync_once: config.sync_once,
+            skip_block_download_wait: config.skip_block_download_wait,
             disable_electrum_rpc: config.disable_electrum_rpc,
             server_banner: config.server_banner,
             signet_magic: magic,

src/daemon.rs

@@ -23,9 +23,13 @@ enum PollResult {
     Retry,
 }
 
-fn rpc_poll(client: &mut Client) -> PollResult {
+fn rpc_poll(client: &mut Client, skip_block_download_wait: bool) -> PollResult {
     match client.get_blockchain_info() {
         Ok(info) => {
+            if skip_block_download_wait {
+                // bitcoind RPC is available, don't wait for block download to finish
+                return PollResult::Done(Ok(()));
+            }
             let left_blocks = info.headers - info.blocks;
             if info.initial_block_download || left_blocks > 0 {
                 info!(
@@ -108,7 +112,7 @@ impl Daemon {
             exit_flag
                 .poll()
                 .context("bitcoin RPC polling interrupted")?;
-            match rpc_poll(&mut rpc) {
+            match rpc_poll(&mut rpc, config.skip_block_download_wait) {
                 PollResult::Done(result) => {
                     result.context("bitcoind RPC polling failed")?;
                     break; // on success, finish polling