From 42c7df936e80371bd8120d51d5cdba1f48408e80 Mon Sep 17 00:00:00 2001
From: Alan Sapede <alan@purestake.com>
Date: Wed, 20 Jul 2022 18:04:31 -0400
Subject: [PATCH] Make reading json genesis file faster (#11868)
* Make reading json genesis file faster
* Formatting
* fmt
---
substrate/client/chain-spec/src/chain_spec.rs | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/substrate/client/chain-spec/src/chain_spec.rs b/substrate/client/chain-spec/src/chain_spec.rs
index efb40d46f21..5aafc28524d 100644
--- a/substrate/client/chain-spec/src/chain_spec.rs
+++ b/substrate/client/chain-spec/src/chain_spec.rs
@@ -61,7 +61,16 @@ impl<G: RuntimeGenesis> GenesisSource<G> {
let file = File::open(path).map_err(|e| {
format!("Error opening spec file at `{}`: {}", path.display(), e)
})?;
- let genesis: GenesisContainer<G> = json::from_reader(file)
+ // SAFETY: `mmap` is fundamentally unsafe since technically the file can change
+ // underneath us while it is mapped; in practice it's unlikely to be a
+ // problem
+ let bytes = unsafe {
+ memmap2::Mmap::map(&file).map_err(|e| {
+ format!("Error mmaping spec file `{}`: {}", path.display(), e)
+ })?
+ };
+
+ let genesis: GenesisContainer<G> = json::from_slice(&bytes)
.map_err(|e| format!("Error parsing spec file: {}", e))?;
Ok(genesis.genesis)
},
--
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