output: move output structures to a crate

rpc-perf periodically takes a snapshot of its observed performance
metrics and outputs them into JSON. Move the structures comprising
this JSON into the rpcperf-dataspec crate so that external consumers
can parse rpc-perf's output by importing the crate from lib/dataspec.

Cargo.toml

@@ -1,13 +1,24 @@
-[package]
-name = "rpc-perf"
-version = "5.0.2-alpha.0"
+[workspace.package]
 authors = ["Brian Martin <brian@iop.systems>"]
 edition = "2021"
-description = "RPC Performance Testing"
 homepage = "https://github.com/iopsystems/rpc-perf"
 repository = "https://github.com/iopsystems/rpc-perf"
 license = "MIT OR Apache-2.0"
 
+[package]
+name = "rpc-perf"
+description = "RPC Performance Testing"
+version = "5.0.2-alpha.0"
+authors = { workspace = true }
+edition = { workspace = true }
+homepage = { workspace = true }
+repository = { workspace = true }
+license = { workspace = true }
+
+[workspace.dependencies]
+histogram = "0.7.4"
+serde = "1.0.144"
+
 [dependencies]
 ahash = "0.8.3"
 async-channel = "1.8.0"
@@ -21,7 +32,7 @@ foreign-types-shared = "0.3.1"
 futures = "0.3.28"
 http-body-util = "0.1.0-rc.2"
 hyper = { version = "1.0.0-rc.3", features = ["http1", "http2", "client"]}
-histogram = "0.7.4"
+histogram = { workspace = true }
 humantime = "2.1.0"
 momento = "0.31.0"
 metriken = "0.2.3"
@@ -36,7 +47,8 @@ rand_xoshiro = "0.6.0"
 ratelimit = "0.7.0"
 redis = { version = "0.22.3", features = ["tokio-comp"] }
 ringlog = "0.2.0"
-serde = "1.0.144"
+rpcperf-dataspec = { path = "lib/dataspec" }
+serde = { workspace = true }
 serde_json = "1.0.94"
 session = { git = "https://github.com/pelikan-io/pelikan" }
 sha2 = "0.10.7"
@@ -47,6 +59,11 @@ toml = "0.7.2"
 zipf = "7.0.0"
 warp = "0.3.4"
 
+[workspace]
+members = [
+    "lib/dataspec",
+]
+
 [profile.release]
 opt-level = 3
 debug = true

lib/dataspec/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "rpcperf-dataspec"
+version = "0.1.0"
+authors = { workspace = true }
+edition = { workspace = true }
+homepage = { workspace = true }
+repository = { workspace = true }
+license = { workspace = true }
+
+[dependencies]
+histogram = { workspace = true }
+serde = { workspace = true }

lib/dataspec/src/lib.rs

@@ -0,0 +1,80 @@
+//! Format of JSON output from rpc-perf. These structures can be used
+//! by any consumer of the produced data to parse the files.
+
+use serde::{Deserialize, Serialize};
+
+use histogram::CompactHistogram;
+
+#[derive(Serialize, Deserialize)]
+pub struct Connections {
+    /// number of current connections (gauge)
+    pub current: i64,
+    /// number of total connect attempts
+    pub total: u64,
+    /// number of connections established
+    pub opened: u64,
+    /// number of connect attempts that failed
+    pub error: u64,
+    /// number of connect attempts that hit timeout
+    pub timeout: u64,
+}
+
+#[derive(Copy, Clone, Serialize, Deserialize)]
+pub struct Requests {
+    pub total: u64,
+    pub ok: u64,
+    pub reconnect: u64,
+    pub unsupported: u64,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Responses {
+    /// total number of responses
+    pub total: u64,
+    /// number of responses that were successful
+    pub ok: u64,
+    /// number of responses that were unsuccessful
+    pub error: u64,
+    /// number of responses that were missed due to timeout
+    pub timeout: u64,
+    /// number of read requests with a hit response
+    pub hit: u64,
+    /// number of read requests with a miss response
+    pub miss: u64,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct ClientStats {
+    pub connections: Connections,
+    pub requests: Requests,
+    pub responses: Responses,
+    pub request_latency: CompactHistogram,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct PubsubStats {
+    pub publishers: Publishers,
+    pub subscribers: Subscribers,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Publishers {
+    // current number of publishers
+    pub current: i64,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Subscribers {
+    // current number of subscribers
+    pub current: i64,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct JsonSnapshot {
+    pub window: u64,
+    pub elapsed: f64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub target_qps: Option<f64>,
+    pub client: ClientStats,
+    pub pubsub: PubsubStats,
+}

src/output/mod.rs

@@ -1,7 +1,8 @@
 use crate::*;
+use rpcperf_dataspec::*;
+
 use ahash::{HashMap, HashMapExt};
 use ratelimit::Ratelimiter;
-use serde::Serialize;
 use std::io::{BufWriter, Write};
 
 use histogram::CompactHistogram;
@@ -219,80 +220,6 @@ fn pubsub_stats(snapshot: &mut Snapshot, elapsed: f64) -> u64 {
     pubsub_tx_ok
 }
 
-#[derive(Serialize)]
-struct Connections {
-    /// number of current connections (gauge)
-    current: i64,
-    /// number of total connect attempts
-    total: u64,
-    /// number of connections established
-    opened: u64,
-    /// number of connect attempts that failed
-    error: u64,
-    /// number of connect attempts that hit timeout
-    timeout: u64,
-}
-
-#[derive(Serialize, Copy, Clone)]
-struct Requests {
-    total: u64,
-    ok: u64,
-    reconnect: u64,
-    unsupported: u64,
-}
-
-#[derive(Serialize)]
-struct Responses {
-    /// total number of responses
-    total: u64,
-    /// number of responses that were successful
-    ok: u64,
-    /// number of responses that were unsuccessful
-    error: u64,
-    /// number of responses that were missed due to timeout
-    timeout: u64,
-    /// number of read requests with a hit response
-    hit: u64,
-    /// number of read requests with a miss response
-    miss: u64,
-}
-
-#[derive(Serialize)]
-struct Client {
-    connections: Connections,
-    requests: Requests,
-    responses: Responses,
-    request_latency: CompactHistogram,
-}
-
-#[derive(Serialize)]
-struct Pubsub {
-    publishers: Publishers,
-    subscribers: Subscribers,
-}
-
-#[derive(Serialize)]
-struct Publishers {
-    // current number of publishers
-    current: i64,
-}
-
-#[derive(Serialize)]
-struct Subscribers {
-    // current number of subscribers
-    current: i64,
-}
-
-#[derive(Serialize)]
-struct JsonSnapshot {
-    window: u64,
-    elapsed: f64,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    target_qps: Option<f64>,
-    client: Client,
-    pubsub: Pubsub,
-}
-
 // gets the non-zero buckets for the most recent window in the heatmap
 fn heatmap_to_buckets(heatmap: &Heatmap) -> CompactHistogram {
     // XXX: The heatmap corrects for wraparound and fixes indices once
@@ -380,13 +307,13 @@ pub fn json(config: Config, ratelimit: Option<&Ratelimiter>) {
                 window: window_id,
                 elapsed,
                 target_qps: ratelimit.as_ref().map(|ratelimit| ratelimit.rate()),
-                client: Client {
+                client: ClientStats {
                     connections,
                     requests,
                     responses,
                     request_latency: heatmap_to_buckets(&REQUEST_LATENCY),
                 },
-                pubsub: Pubsub {
+                pubsub: PubsubStats {
                     publishers: Publishers {
                         current: PUBSUB_PUBLISHER_CURR.value(),
                     },