backend in rust WIP

backend-rust/.gitignore

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+.idea
+*.iml

backend-rust/Cargo.toml

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+[package]
+name = "fluid"
+version = "0.1.0"
+authors = ["Fluence Labs"]
+publish = false
+description = "Decentralized feed built on Fluence"
+edition = "2018"
+
+[lib]
+name = "fluid"
+path = "src/lib.rs"
+crate-type = ["cdylib"]
+
+[profile.release]
+debug = false
+lto = true
+opt-level = "z"
+panic = "abort"
+
+[dependencies]
+log = "0.4"
+fluence = { version = "0.1.6", features = ["wasm_logger"] }

backend-rust/src/main.rs

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+use fluence::sdk::*;
+use log::info;
+
+fn init() {
+    logger::WasmLogger::init_with_level(log::Level::Info).unwrap();
+}
+
+#[invocation_handler(init_fn = init)]
+fn main(arg: String) -> String {
+    println!("Hello, world!");
+
+    let query = "CREATE VIRTUAL TABLE users USING FTS5(body)";
+    unsafe {
+        let bytes = query.as_bytes();
+        let query_ptr = allocate(bytes.len());
+        for (i, byte) in bytes.iter().enumerate() {
+            let ptr = query_ptr as usize + 8*i;
+            store(ptr, *byte);
+        }
+
+        let result_ptr = invoke(query_ptr, bytes.len());
+
+        let mut result_size = 0;
+        for i in 0..4 {
+            let ptr = (result_ptr + 8*i) as usize;
+            b = load(ptr);
+            result_size = result_size | (b >> 8*i)
+        }
+
+        let mut result_bytes: &[u8] = &[0 as u8; result_size];
+        for i in 0..result_size {
+            let ptr = (result_ptr + 8*i) as usize;
+            b = load(ptr);
+            result_bytes[i] = b;
+        }
+
+        let result_str = std::str::from_utf8(result_bytes);
+        if result_str.is_err() {
+            info!("unable to decode result from result_bytes: {}", result_bytes);
+        }
+
+        info!("result is {}", result_str);
+
+        result_str.expect("unable to decode result").to_string()
+    }
+}
+
+#[link(wasm_import_module = "sqlite")]
+extern "C" {
+    fn allocate(size: usize) -> i32;
+    fn deallocate(ptr: i32, size: usize) -> void;
+    fn invoke(ptr: i32, size: usize) -> i32;
+    fn store(ptr: usize, byte: u8) -> void;
+    fn load(ptr: usize) -> u8;
+}