Npy tweaks & error with path (#384)

* Simplify the npy writing.

* Wrap the file path so as to provide better errors.

candle-core/src/error.rs

@@ -185,6 +185,13 @@ pub enum Error {
     #[error(transparent)]
     Wrapped(Box<dyn std::error::Error + Send + Sync>),
 
+    /// Adding path information to an error.
+    #[error("path: {path:?} {inner}")]
+    WithPath {
+        inner: Box<Self>,
+        path: std::path::PathBuf,
+    },
+
     #[error("{inner}\n{backtrace}")]
     WithBacktrace {
         inner: Box<Self>,
@@ -214,6 +221,13 @@ impl Error {
             },
         }
     }
+
+    pub fn with_path<P: AsRef<std::path::Path>>(self, p: P) -> Self {
+        Self::WithPath {
+            inner: Box::new(self),
+            path: p.as_ref().to_path_buf(),
+        }
+    }
 }
 
 #[macro_export]

candle-core/src/npy.rs

@@ -307,39 +307,39 @@ impl Tensor {
         header.push('\n');
         f.write_all(&[(header.len() % 256) as u8, (header.len() / 256) as u8])?;
         f.write_all(header.as_bytes())?;
-        let elem_count = self.elem_count();
+        let vs = self.flatten_all()?;
         match self.dtype() {
             DType::BF16 => {
-                let vs = self.reshape(elem_count)?.to_vec1::<bf16>()?;
+                let vs = vs.to_vec1::<bf16>()?;
                 for &v in vs.reinterpret_cast() {
                     f.write_u16::<LittleEndian>(v)?
                 }
             }
             DType::F16 => {
-                let vs = self.reshape(elem_count)?.to_vec1::<f16>()?;
+                let vs = vs.to_vec1::<f16>()?;
                 for &v in vs.reinterpret_cast() {
                     f.write_u16::<LittleEndian>(v)?
                 }
             }
             DType::F32 => {
                 // TODO: Avoid using a buffer when data is already on the CPU.
-                for v in self.reshape(elem_count)?.to_vec1::<f32>()? {
+                for v in vs.to_vec1::<f32>()? {
                     f.write_f32::<LittleEndian>(v)?
                 }
             }
             DType::F64 => {
-                for v in self.reshape(elem_count)?.to_vec1::<f64>()? {
+                for v in vs.to_vec1::<f64>()? {
                     f.write_f64::<LittleEndian>(v)?
                 }
             }
             DType::U32 => {
-                for v in self.reshape(elem_count)?.to_vec1::<u32>()? {
+                for v in vs.to_vec1::<u32>()? {
                     f.write_u32::<LittleEndian>(v)?
                 }
             }
             DType::U8 => {
-                let data = self.reshape(elem_count)?.to_vec1::<u8>()?;
+                let vs = vs.to_vec1::<u8>()?;
-                f.write_all(&data)?;
+                f.write_all(&vs)?;
             }
         }
         Ok(())
@@ -373,7 +373,7 @@ pub struct NpzTensors {
     index_per_name: HashMap<String, usize>,
     path: std::path::PathBuf,
     // We do not store a zip reader as it needs mutable access to extract data. Instead we
-    // re-create a zip reader each time.
+    // re-create a zip reader for each tensor.
 }
 
 impl NpzTensors {

candle-core/src/safetensors.rs

@@ -257,7 +257,10 @@ pub fn save<P: AsRef<Path>>(tensors: &HashMap<&str, Tensor>, filename: P) -> Res
     Ok(st::serialize_to_file(tensors, &None, filename.as_ref())?)
 }
 
-pub struct MmapedFile(memmap2::Mmap);
+pub struct MmapedFile {
+    path: std::path::PathBuf,
+    inner: memmap2::Mmap,
+}
 
 impl MmapedFile {
     /// Creates a wrapper around a memory mapped file from which you can retrieve
@@ -267,13 +270,20 @@ impl MmapedFile {
     ///
     /// The unsafe is inherited from [`memmap2::MmapOptions`].
     pub unsafe fn new<P: AsRef<std::path::Path>>(p: P) -> Result<Self> {
-        let file = std::fs::File::open(p)?;
+        let p = p.as_ref();
-        let mmap = memmap2::MmapOptions::new().map(&file)?;
+        let file = std::fs::File::open(p).map_err(|e| Error::from(e).with_path(p))?;
-        Ok(Self(mmap))
+        let inner = memmap2::MmapOptions::new()
+            .map(&file)
+            .map_err(|e| Error::from(e).with_path(p))?;
+        Ok(Self {
+            inner,
+            path: p.to_path_buf(),
+        })
     }
 
     pub fn deserialize(&self) -> Result<SafeTensors<'_>> {
-        let st = safetensors::SafeTensors::deserialize(&self.0)?;
+        let st = safetensors::SafeTensors::deserialize(&self.inner)
+            .map_err(|e| Error::from(e).with_path(&self.path))?;
         Ok(st)
     }
 }