From 5d33b898dffa2c4a963b46904a746aabfb8f11bb Mon Sep 17 00:00:00 2001
From: Daniel Sanchez Quiros <sanchez.quiros.daniel@gmail.com>
Date: Fri, 30 Sep 2022 22:04:56 +0200
Subject: [PATCH] Use shared state to store callback closures for waku
 callbacks

---
 Cargo.lock             | 464 +----------------------------------------
 waku/Cargo.toml        |   1 +
 waku/src/events/mod.rs |  42 ++--
 3 files changed, 32 insertions(+), 475 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index d680613..9c70bbd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -11,12 +11,6 @@ dependencies = [
  "memchr",
 ]
 
-[[package]]
-name = "arrayref"
-version = "0.3.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a4c527152e37cf757a3f78aae5a06fbeefdb07ccc535c980a3208ee3060dd544"
-
 [[package]]
 name = "atty"
 version = "0.2.14"
@@ -34,12 +28,6 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
-[[package]]
-name = "base64"
-version = "0.13.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "904dfeac50f3cdaba28fc6f57fdcddb75f49ed61346676a78c4ffe55877802fd"
-
 [[package]]
 name = "bindgen"
 version = "0.60.1"
@@ -69,27 +57,6 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
-[[package]]
-name = "block-buffer"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4152116fd6e9dadb291ae18fc1ec3575ed6d84c29642d97890f4b4a3417297e4"
-dependencies = [
- "generic-array",
-]
-
-[[package]]
-name = "bs58"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "771fe0050b883fcc3ea2359b1a96bcfbc090b7116eae7c3c512c7a083fdf23d3"
-
-[[package]]
-name = "byteorder"
-version = "1.4.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "14c189c53d098945499cdfa7ecc63567cf3886b3332b312a5b4585d8d3a6a610"
-
 [[package]]
 name = "cexpr"
 version = "0.6.0"
@@ -140,55 +107,6 @@ dependencies = [
  "os_str_bytes",
 ]
 
-[[package]]
-name = "core2"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b49ba7ef1ad6107f8824dbe97de947cbaac53c44e7f9756a1fba0d37c1eec505"
-dependencies = [
- "memchr",
-]
-
-[[package]]
-name = "cpufeatures"
-version = "0.2.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "28d997bd5e24a5928dd43e46dc529867e207907fe0b239c3477d924f7f2ca320"
-dependencies = [
- "libc",
-]
-
-[[package]]
-name = "crunchy"
-version = "0.2.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a81dae078cea95a014a339291cec439d2f232ebe854a9d672b796c6afafa9b7"
-
-[[package]]
-name = "crypto-mac"
-version = "0.8.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b584a330336237c1eecd3e94266efb216c56ed91225d634cb2991c5f3fd1aeab"
-dependencies = [
- "generic-array",
- "subtle",
-]
-
-[[package]]
-name = "data-encoding"
-version = "2.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ee2393c4a91429dffb4bedf19f4d6abf27d8a732c8ce4980305d782e5426d57"
-
-[[package]]
-name = "digest"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d3dd60d1080a57a05ab032377049e0591415d2b31afd7028356dbf3cc6dcb066"
-dependencies = [
- "generic-array",
-]
-
 [[package]]
 name = "either"
 version = "1.8.0"
@@ -208,36 +126,6 @@ dependencies = [
  "termcolor",
 ]
 
-[[package]]
-name = "form_urlencoded"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9c384f161156f5260c24a097c56119f9be8c798586aecc13afbcbe7b7e26bf8"
-dependencies = [
- "percent-encoding",
-]
-
-[[package]]
-name = "generic-array"
-version = "0.14.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bff49e947297f3312447abdca79f45f4738097cc82b06e72054d2223f601f1b9"
-dependencies = [
- "typenum",
- "version_check",
-]
-
-[[package]]
-name = "getrandom"
-version = "0.2.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4eb1a864a501629691edf6c15a593b7a51eebaa1e8468e9ddc623de7c9b58ec6"
-dependencies = [
- "cfg-if",
- "libc",
- "wasi",
-]
-
 [[package]]
 name = "glob"
 version = "0.3.0"
@@ -259,49 +147,12 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "hex"
-version = "0.4.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
-
-[[package]]
-name = "hmac"
-version = "0.8.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "126888268dcc288495a26bf004b38c5fdbb31682f992c84ceb046a1f0fe38840"
-dependencies = [
- "crypto-mac",
- "digest",
-]
-
-[[package]]
-name = "hmac-drbg"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "17ea0a1394df5b6574da6e0c1ade9e78868c9fb0a4e5ef4428e32da4676b85b1"
-dependencies = [
- "digest",
- "generic-array",
- "hmac",
-]
-
 [[package]]
 name = "humantime"
 version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a3a5bfb195931eeb336b2a7b4d761daec841b97f947d34394601737a7bba5e4"
 
-[[package]]
-name = "idna"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e14ddfc70884202db2244c223200c204c2bda1bc6e0998d11b5e024d657209e6"
-dependencies = [
- "unicode-bidi",
- "unicode-normalization",
-]
-
 [[package]]
 name = "indexmap"
 version = "1.9.1"
@@ -346,54 +197,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "libsecp256k1"
-version = "0.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "95b09eff1b35ed3b33b877ced3a691fc7a481919c7e29c53c906226fcf55e2a1"
-dependencies = [
- "arrayref",
- "base64",
- "digest",
- "hmac-drbg",
- "libsecp256k1-core",
- "libsecp256k1-gen-ecmult",
- "libsecp256k1-gen-genmult",
- "rand",
- "serde",
- "sha2",
- "typenum",
-]
-
-[[package]]
-name = "libsecp256k1-core"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5be9b9bb642d8522a44d533eab56c16c738301965504753b03ad1de3425d5451"
-dependencies = [
- "crunchy",
- "digest",
- "subtle",
-]
-
-[[package]]
-name = "libsecp256k1-gen-ecmult"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3038c808c55c87e8a172643a7d87187fc6c4174468159cb3090659d55bcb4809"
-dependencies = [
- "libsecp256k1-core",
-]
-
-[[package]]
-name = "libsecp256k1-gen-genmult"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3db8d6ba2cec9eacc40e6e8ccc98931840301f1006e95647ceb2dd5c3aa06f7c"
-dependencies = [
- "libsecp256k1-core",
-]
-
 [[package]]
 name = "log"
 version = "0.4.17"
@@ -415,49 +218,6 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
 
-[[package]]
-name = "multiaddr"
-version = "0.14.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c580bfdd8803cce319b047d239559a22f809094aaea4ac13902a1fdcfcd4261"
-dependencies = [
- "arrayref",
- "bs58",
- "byteorder",
- "data-encoding",
- "multihash",
- "percent-encoding",
- "serde",
- "static_assertions",
- "unsigned-varint",
- "url",
-]
-
-[[package]]
-name = "multihash"
-version = "0.16.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1c346cf9999c631f002d8f977c4eaeaa0e6386f16007202308d0b3757522c2cc"
-dependencies = [
- "core2",
- "multihash-derive",
- "unsigned-varint",
-]
-
-[[package]]
-name = "multihash-derive"
-version = "0.8.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fc076939022111618a5026d3be019fd8b366e76314538ff9a1b59ffbcbf98bcd"
-dependencies = [
- "proc-macro-crate",
- "proc-macro-error",
- "proc-macro2",
- "quote",
- "syn",
- "synstructure",
-]
-
 [[package]]
 name = "nom"
 version = "7.1.1"
@@ -474,12 +234,6 @@ version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e82dad04139b71a90c080c8463fe0dc7902db5192d939bd0950f074d014339e1"
 
-[[package]]
-name = "opaque-debug"
-version = "0.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "624a8340c38c1b80fd549087862da4ba43e08858af025b236e509b6649fc13d5"
-
 [[package]]
 name = "os_str_bytes"
 version = "6.3.0"
@@ -492,53 +246,6 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "19b17cddbe7ec3f8bc800887bab5e717348c95ea2ca0b1bf0837fb964dc67099"
 
-[[package]]
-name = "percent-encoding"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "478c572c3d73181ff3c2539045f6eb99e5491218eae919370993b890cdbdd98e"
-
-[[package]]
-name = "ppv-lite86"
-version = "0.2.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eb9f9e6e233e5c4a35559a617bf40a4ec447db2e84c20b55a6f83167b7e57872"
-
-[[package]]
-name = "proc-macro-crate"
-version = "1.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eda0fc3b0fb7c975631757e14d9049da17374063edb6ebbcbc54d880d4fe94e9"
-dependencies = [
- "once_cell",
- "thiserror",
- "toml",
-]
-
-[[package]]
-name = "proc-macro-error"
-version = "1.0.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
-dependencies = [
- "proc-macro-error-attr",
- "proc-macro2",
- "quote",
- "syn",
- "version_check",
-]
-
-[[package]]
-name = "proc-macro-error-attr"
-version = "1.0.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
-dependencies = [
- "proc-macro2",
- "quote",
- "version_check",
-]
-
 [[package]]
 name = "proc-macro2"
 version = "1.0.43"
@@ -557,36 +264,6 @@ dependencies = [
  "proc-macro2",
 ]
 
-[[package]]
-name = "rand"
-version = "0.8.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
-dependencies = [
- "libc",
- "rand_chacha",
- "rand_core",
-]
-
-[[package]]
-name = "rand_chacha"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
-dependencies = [
- "ppv-lite86",
- "rand_core",
-]
-
-[[package]]
-name = "rand_core"
-version = "0.6.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
-dependencies = [
- "getrandom",
-]
-
 [[package]]
 name = "regex"
 version = "1.6.0"
@@ -647,43 +324,18 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "sha2"
-version = "0.9.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4d58a1e1bf39749807d89cf2d98ac2dfa0ff1cb3faa38fbb64dd88ac8013d800"
-dependencies = [
- "block-buffer",
- "cfg-if",
- "cpufeatures",
- "digest",
- "opaque-debug",
-]
-
 [[package]]
 name = "shlex"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "43b2853a4d09f215c24cc5489c992ce46052d359b5109343cbafbf26bc62f8a3"
 
-[[package]]
-name = "static_assertions"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
-
 [[package]]
 name = "strsim"
 version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
-[[package]]
-name = "subtle"
-version = "2.4.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6bdef32e8150c2a081110b42772ffe7d7c9032b606bc226c8260fd97e0976601"
-
 [[package]]
 name = "syn"
 version = "1.0.100"
@@ -695,18 +347,6 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "synstructure"
-version = "0.12.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f36bdaa60a83aca3921b5259d5400cbf5e90fc51931376a9bd4a0eb79aa7210f"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
- "unicode-xid",
-]
-
 [[package]]
 name = "termcolor"
 version = "1.1.3"
@@ -722,113 +362,17 @@ version = "0.15.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "949517c0cf1bf4ee812e2e07e08ab448e3ae0d23472aee8a06c985f0c8815b16"
 
-[[package]]
-name = "thiserror"
-version = "1.0.37"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "10deb33631e3c9018b9baf9dcbbc4f737320d2b576bac10f6aefa048fa407e3e"
-dependencies = [
- "thiserror-impl",
-]
-
-[[package]]
-name = "thiserror-impl"
-version = "1.0.37"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "982d17546b47146b28f7c22e3d08465f6b8903d0ea13c1660d9d84a6e7adcdbb"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
-[[package]]
-name = "tinyvec"
-version = "1.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "87cc5ceb3875bb20c2890005a4e226a4651264a5c75edb2421b52861a0a0cb50"
-dependencies = [
- "tinyvec_macros",
-]
-
-[[package]]
-name = "tinyvec_macros"
-version = "0.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cda74da7e1a664f795bb1f8a87ec406fb89a02522cf6e50620d016add6dbbf5c"
-
-[[package]]
-name = "toml"
-version = "0.5.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8d82e1a7758622a465f8cee077614c73484dac5b836c02ff6a40d5d1010324d7"
-dependencies = [
- "serde",
-]
-
-[[package]]
-name = "typenum"
-version = "1.15.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dcf81ac59edc17cc8697ff311e8f5ef2d99fcbd9817b34cec66f90b6c3dfd987"
-
-[[package]]
-name = "unicode-bidi"
-version = "0.3.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "099b7128301d285f79ddd55b9a83d5e6b9e97c92e0ea0daebee7263e932de992"
-
 [[package]]
 name = "unicode-ident"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dcc811dc4066ac62f84f11307873c4850cb653bfa9b1719cee2bd2204a4bc5dd"
 
-[[package]]
-name = "unicode-normalization"
-version = "0.1.22"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5c5713f0fc4b5db668a2ac63cdb7bb4469d8c9fed047b1d0292cc7b0ce2ba921"
-dependencies = [
- "tinyvec",
-]
-
-[[package]]
-name = "unicode-xid"
-version = "0.2.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f962df74c8c05a667b5ee8bcf162993134c104e96440b663c8daa176dc772d8c"
-
-[[package]]
-name = "unsigned-varint"
-version = "0.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d86a8dc7f45e4c1b0d30e43038c38f274e77af056aa5f74b93c2cf9eb3c1c836"
-
-[[package]]
-name = "url"
-version = "2.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0d68c799ae75762b8c3fe375feb6600ef5602c883c5d21eb51c09f22b83c4643"
-dependencies = [
- "form_urlencoded",
- "idna",
- "percent-encoding",
-]
-
-[[package]]
-name = "version_check"
-version = "0.9.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
-
 [[package]]
 name = "waku"
 version = "0.1.0"
 dependencies = [
- "hex",
- "libsecp256k1",
- "multiaddr",
+ "once_cell",
  "serde",
  "serde_json",
  "waku-sys",
@@ -841,12 +385,6 @@ dependencies = [
  "bindgen",
 ]
 
-[[package]]
-name = "wasi"
-version = "0.11.0+wasi-snapshot-preview1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
-
 [[package]]
 name = "which"
 version = "4.3.0"
diff --git a/waku/Cargo.toml b/waku/Cargo.toml
index 8acbf30..0c23ead 100644
--- a/waku/Cargo.toml
+++ b/waku/Cargo.toml
@@ -9,6 +9,7 @@ edition = "2021"
 hex = "0.4"
 libsecp256k1 = "0.7"
 multiaddr = "0.14"
+once_cell = "1.15"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 waku-sys = { path = "../waku-sys" }
diff --git a/waku/src/events/mod.rs b/waku/src/events/mod.rs
index 1d859d1..39ffdd2 100644
--- a/waku/src/events/mod.rs
+++ b/waku/src/events/mod.rs
@@ -1,6 +1,9 @@
 // std
 use std::ffi::{c_char, CStr};
+use std::ops::Deref;
+use std::sync::RwLock;
 // crates
+use once_cell::sync::Lazy;
 use serde::{Deserialize, Serialize};
 // internal
 use crate::general::{PubsubTopic, WakuMessage};
@@ -44,20 +47,35 @@ impl WakuMessageEvent {
     }
 }
 
+/// Shared callback slot. Callbacks are registered here so they can be accessed by the extern "C"
+#[allow(clippy::type_complexity)]
+static CALLBACK: Lazy<RwLock<Box<dyn FnMut(Signal) + Send + Sync>>> =
+    Lazy::new(|| RwLock::new(Box::new(|_| {})));
+
+/// Register global callback
+fn set_callback<F: FnMut(Signal) + Send + Sync + 'static>(f: F) {
+    *CALLBACK.write().unwrap() = Box::new(f);
+}
+
+/// Wrapper callback, it transformst the `*const c_char` into a [`Signal`]
+/// and executes the [`CALLBACK`] funtion with it
+extern "C" fn callback(data: *const c_char) {
+    let raw_response = unsafe { CStr::from_ptr(data) }
+        .to_str()
+        .expect("Not null ptr");
+    let data: Signal = serde_json::from_str(raw_response).expect("Parsing signal to succeed");
+    (CALLBACK
+        .deref()
+        .write()
+        .expect("Access to the shared callback")
+        .as_mut())(data)
+}
+
 /// Register callback to act as event handler and receive application signals,
 /// which are used to react to asynchronous events in Waku
-pub fn waku_set_event_callback<F: FnMut(Signal)>(mut callback: F) {
-    let mut callback_wrapper = move |data: *const c_char| {
-        let raw_response = unsafe { CStr::from_ptr(data) }
-            .to_str()
-            .expect("Not null ptr");
-        let data: Signal = serde_json::from_str(raw_response).expect("Parsing signal to succeed");
-        callback(data);
-    };
-    let mut callback_ptr: &mut dyn FnMut(*const c_char) = &mut callback_wrapper;
-    unsafe {
-        waku_sys::waku_set_event_callback(&mut callback_ptr as *mut &mut _ as *mut std::ffi::c_void)
-    };
+pub fn waku_set_event_callback<F: FnMut(Signal) + Send + Sync + 'static>(f: F) {
+    set_callback(f);
+    unsafe { waku_sys::waku_set_event_callback(&mut callback as *mut _ as *mut std::ffi::c_void) };
 }
 
 #[cfg(test)]