Make the cuda rng seedable. (#1056)

candle-core/src/backend.rs

@@ -111,4 +111,6 @@ pub trait BackendDevice: Sized + std::fmt::Debug + Clone {
     fn rand_uniform(&self, _: &Shape, _: DType, _: f64, _: f64) -> Result<Self::Storage>;
 
     fn rand_normal(&self, _: &Shape, _: DType, _: f64, _: f64) -> Result<Self::Storage>;
+
+    fn set_seed(&self, _: u64) -> Result<()>;
 }

candle-core/src/cpu_backend.rs

@@ -2603,6 +2603,10 @@ impl BackendDevice for CpuDevice {
         Ok(Self)
     }
 
+    fn set_seed(&self, _seed: u64) -> Result<()> {
+        crate::bail!("cannot seed the CPU rng with set_seed")
+    }
+
     fn rand_uniform(&self, shape: &Shape, dtype: DType, min: f64, max: f64) -> Result<CpuStorage> {
         use rand::prelude::*;
 

candle-core/src/cuda_backend.rs

@@ -223,6 +223,12 @@ impl BackendDevice for CudaDevice {
         })
     }
 
+    fn set_seed(&self, seed: u64) -> Result<()> {
+        let mut curand = self.curand.lock().unwrap();
+        curand.0.set_seed(seed).w()?;
+        Ok(())
+    }
+
     fn location(&self) -> crate::DeviceLocation {
         crate::DeviceLocation::Cuda {
             gpu_id: self.device.ordinal(),

candle-core/src/dummy_cuda_backend.rs

@@ -167,6 +167,10 @@ impl crate::backend::BackendDevice for CudaDevice {
         Err(Error::NotCompiledWithCudaSupport)
     }
 
+    fn set_seed(&self, _: u64) -> Result<()> {
+        Err(Error::NotCompiledWithCudaSupport)
+    }
+
     fn location(&self) -> crate::DeviceLocation {
         fail!()
     }