Merge 'Added random number generation to I/O trait for simulation' fr…

…om mason

Took a stab at the RNG portion of this [issue](#272), do let me know if there's anything that I can improve on/rework!

Thanks!

Closes #301

bindings/wasm/lib.rs

@@ -87,6 +87,16 @@ impl limbo_core::IO for PlatformIO {
     fn run_once(&self) -> Result<()> {
         Ok(())
     }
+
+    fn generate_random_number(&self) -> i64 {
+        let random_f64 = Math_random();
+        (random_f64 * i64::MAX as f64) as i64
+    }
+}
+
+#[wasm_bindgen]
+extern "C" {
+    fn Math_random() -> f64;
 }
 
 pub struct DatabaseStorage {

core/io/darwin.rs

@@ -104,6 +104,12 @@ impl IO for DarwinIO {
         }
         Ok(())
     }
+
+    fn generate_random_number(&self) -> i64 {
+        let mut buf = [0u8; 8];
+        getrandom::getrandom(&mut buf).unwrap();
+        i64::from_ne_bytes(buf)
+    }
 }
 
 enum CompletionCallback {

core/io/generic.rs

@@ -24,6 +24,12 @@ impl IO for GenericIO {
     fn run_once(&self) -> Result<()> {
         Ok(())
     }
+
+    fn generate_random_number(&self) -> i64 {
+        let mut buf = [0u8; 8];
+        getrandom::getrandom(&mut buf).unwrap();
+        i64::from_ne_bytes(buf)
+    }
 }
 
 pub struct GenericFile {

core/io/linux.rs

@@ -105,6 +105,12 @@ impl IO for LinuxIO {
         }
         Ok(())
     }
+
+    fn generate_random_number(&self) -> i64 {
+        let mut buf = [0u8; 8];
+        getrandom::getrandom(&mut buf).unwrap();
+        i64::from_ne_bytes(buf)
+    }
 }
 
 pub struct LinuxFile {

core/io/mod.rs

@@ -20,6 +20,8 @@ pub trait IO {
     fn open_file(&self, path: &str) -> Result<Rc<dyn File>>;
 
     fn run_once(&self) -> Result<()>;
+
+    fn generate_random_number(&self) -> i64;
 }
 
 pub type Complete = dyn Fn(Rc<RefCell<Buffer>>);

core/io/windows.rs

@@ -24,6 +24,12 @@ impl IO for WindowsIO {
     fn run_once(&self) -> Result<()> {
         Ok(())
     }
+
+    fn generate_random_number(&self) -> i64 {
+        let mut buf = [0u8; 8];
+        getrandom::getrandom(&mut buf).unwrap();
+        i64::from_ne_bytes(buf)
+    }
 }
 
 pub struct WindowsFile {

simulator/main.rs

@@ -12,7 +12,7 @@ fn main() {
     };
     println!("Seed: {}", seed);
     let mut rng = ChaCha8Rng::seed_from_u64(seed);
-    let io = Arc::new(SimulatorIO::new().unwrap());
+    let io = Arc::new(SimulatorIO::new(seed).unwrap());
     let db = match Database::open_file(io.clone(), "./testing/testing.db") {
         Ok(db) => db,
         Err(_) => todo!(),
@@ -56,17 +56,20 @@ struct SimulatorIO {
     inner: Box<dyn IO>,
     fault: RefCell<bool>,
     files: RefCell<Vec<Rc<SimulatorFile>>>,
+    rng: RefCell<ChaCha8Rng>,
 }
 
 impl SimulatorIO {
-    fn new() -> Result<Self> {
+    fn new(seed: u64) -> Result<Self> {
         let inner = Box::new(PlatformIO::new()?);
         let fault = RefCell::new(false);
         let files = RefCell::new(Vec::new());
+        let rng = RefCell::new(ChaCha8Rng::seed_from_u64(seed));
         Ok(Self {
             inner,
             fault,
             files,
+            rng,
         })
     }
 
@@ -106,6 +109,10 @@ impl IO for SimulatorIO {
         self.inner.run_once().unwrap();
         Ok(())
     }
+
+    fn generate_random_number(&self) -> i64 {
+        self.rng.borrow_mut().next_u64() as i64
+    }
 }
 
 struct SimulatorFile {