Add the skeleton for the flamegraph target binary

Cargo.toml

@@ -39,6 +39,7 @@ members = [
     "core/lib/balancer",
 
     # Test infrastructure
+    "core/tests/flamegraph_target",
     "core/tests/test_account",
     "core/tests/testkit",
     "core/tests/loadnext",

core/tests/flamegraph_target/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "flamegraph_target"
+version = "0.1.0"
+edition = "2018"
+authors = ["The Matter Labs Team <[email protected]>"]
+homepage = "https://zksync.io/"
+repository = "https://github.com/matter-labs/zksync"
+license = "Apache-2.0"
+keywords = ["blockchain", "zksync"]
+categories = ["cryptography"]
+publish = false # We don't want to publish our tests.
+
+[dependencies]
+zksync_crypto = { path = "../../lib/crypto", version = "1.0" }
+structopt = "0.3.20"

core/tests/flamegraph_target/README.md

@@ -0,0 +1,22 @@
+# zkSync flamegraph target
+
+This binary is a playground for analyzing the performance of the zkSync components, using tools
+such as [perf] and [cargo-flamegraph].
+
+While analyzing the performance of the application overall may be useful, it doesn't really help
+when you want to analyze one particular component when it takes ~100% of the runtime, in order to
+see weak points clearly.
+
+[perf]: https://perf.wiki.kernel.org/index.php/Main_Page
+[cargo-flamegraph]: https://github.com/flamegraph-rs/flamegraph
+
+## Design notes
+
+Since the goal is to avoid *everything* that is not related to the analysis of the particular component,
+try to avoid "hidden" runtime logic such as async runtimes (e.g. `tokio::main`) or logging (e.g. `vlog`)
+in this crate. If the code you are going to analyze requires `async` support, explicitly create the runtime
+for said code only.
+
+Target code should be written in a manner that stresses component in the most possible way.
+If your code needs initialization, separate it from the actual stressing logic, so that in the resulting
+flamegraph they will be easily distinguishable.

core/tests/flamegraph_target/src/main.rs

@@ -0,0 +1 @@
+fn main() {}