feat: rate limit event creation

A configuration option, `messages_per_sec`, imposes a global limit on
the rate for which new events can be stored.

Fixes https://todo.sr.ht/~gheartsfield/nostr-rs-relay/6

Cargo.lock

@@ -81,6 +81,12 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "bumpalo"
+version = "3.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f1e260c3a9040a7c19a12468758f4c16f31a81a1fe087482be9570ec864bb6c"
+
 [[package]]
 name = "byteorder"
 version = "1.4.3"
@@ -139,6 +145,27 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d82cfc11ce7f2c3faef78d8a684447b40d503d9681acebed6cb728d45940c4db"
+dependencies = [
+ "cfg-if",
+ "lazy_static",
+]
+
+[[package]]
+name = "dashmap"
+version = "5.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b799062aaf67eb976af3bdca031ee6f846d2f0a5710ddbb0d2efee33f3cc4760"
+dependencies = [
+ "cfg-if",
+ "num_cpus",
+ "parking_lot",
+]
+
 [[package]]
 name = "digest"
 version = "0.9.0"
@@ -266,6 +293,12 @@ version = "0.3.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dabf1872aaab32c886832f2276d2f5399887e2bd613698a02359e4ea83f8de12"
 
+[[package]]
+name = "futures-timer"
+version = "3.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e64b03909df88034c26dc1547e8970b91f98bdb65165d6a4e9110d94263dbb2c"
+
 [[package]]
 name = "futures-util"
 version = "0.3.18"
@@ -305,6 +338,23 @@ dependencies = [
  "wasi",
 ]
 
+[[package]]
+name = "governor"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3de427a64787873c3b196285e6684cddbf0ae7d1d8d56eaafbb4120c4cb641"
+dependencies = [
+ "dashmap",
+ "futures",
+ "futures-timer",
+ "no-std-compat",
+ "nonzero_ext",
+ "parking_lot",
+ "quanta",
+ "rand 0.8.4",
+ "smallvec",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.11.2"
@@ -387,6 +437,15 @@ version = "0.4.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b71991ff56294aa922b450139ee08b3bfc70982c6b2c7562771375cf73542dd4"
 
+[[package]]
+name = "js-sys"
+version = "0.3.55"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7cc9ffccd38c451a86bf13657df244e9c3f37493cce8e5e21e940963777acc84"
+dependencies = [
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
@@ -446,6 +505,15 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "mach"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b823e83b2affd8f40a9ee8c29dbc56404c1e34cd2710921f2801e2cf29527afa"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "matches"
 version = "0.1.9"
@@ -480,6 +548,12 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "no-std-compat"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b93853da6d84c2e3c7d730d6473e8817692dd89be387eb01b94d7f108ecb5b8c"
+
 [[package]]
 name = "nom"
 version = "5.1.2"
@@ -491,6 +565,12 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "nonzero_ext"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38bf9645c8b145698bb0b18a4637dcacbc421ea49bef2317e4fd8065a387cf21"
+
 [[package]]
 name = "nostr-rs-relay"
 version = "0.1.6"
@@ -500,9 +580,11 @@ dependencies = [
  "env_logger",
  "futures",
  "futures-util",
+ "governor",
  "hex",
  "lazy_static",
  "log",
+ "nonzero_ext",
  "rusqlite",
  "secp256k1",
  "serde 1.0.131",
@@ -627,6 +709,22 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "quanta"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "20afe714292d5e879d8b12740aa223c6a88f118af41870e8b6196e39a02238a8"
+dependencies = [
+ "crossbeam-utils",
+ "libc",
+ "mach",
+ "once_cell",
+ "raw-cpuid",
+ "wasi",
+ "web-sys",
+ "winapi",
+]
+
 [[package]]
 name = "quote"
 version = "1.0.10"
@@ -782,6 +880,15 @@ dependencies = [
  "rand_core 0.3.1",
 ]
 
+[[package]]
+name = "raw-cpuid"
+version = "10.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "929f54e29691d4e6a9cc558479de70db7aa3d98cd6fe7ab86d7507aa2886b9d2"
+dependencies = [
+ "bitflags",
+]
+
 [[package]]
 name = "rdrand"
 version = "0.4.0"
@@ -1158,6 +1265,70 @@ version = "0.10.2+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
 
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "632f73e236b219150ea279196e54e610f5dbafa5d61786303d4da54f84e47fce"
+dependencies = [
+ "cfg-if",
+ "wasm-bindgen-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-backend"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a317bf8f9fba2476b4b2c85ef4c4af8ff39c3c7f0cdfeed4f82c34a880aa837b"
+dependencies = [
+ "bumpalo",
+ "lazy_static",
+ "log",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d56146e7c495528bf6587663bea13a8eb588d39b36b679d83972e1a2dbbdacf9"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7803e0eea25835f8abdc585cd3021b3deb11543c6fe226dcd30b228857c5c5ab"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-backend",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.78"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0237232789cf037d5480773fe568aac745bfe2afbc11a863e97901780a6b47cc"
+
+[[package]]
+name = "web-sys"
+version = "0.3.55"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38eb105f1c59d9eaa6b5cdc92b859d85b926e82cb2e0945cd0c9259faa6fe9fb"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"