WritingSafeTensors generates sharded index

_safetensors.py

@@ -10,71 +10,152 @@ import torch
 # an organized approach would be to separate it into two classes
 
 # what would the internal interface provided to the outer class look like?
+# ... well ...
+#  it accumulates tensors, and a header, and needs to write the whole file
+#  an outer class would basically compose all the functions and little
+#  implementation logic. it might need an extra function to rename the
+#  file. that's all!
 
 
 class WritingSafeTensors:
-    def __init__(self, filename, max_size=16*1024*1024*1024, **metadata):
-        self.filename = filename
-        self.fd = os.open(self.filename, os.O_RDWR | os.O_CREAT)
-        self.size = 0
-        self.capacity = 0
-        self.mmapview = None
-        self.header = {'__metadata__': {k:str(v) for k,v in metadata.items()}}
-    def _reserve(self, length):
-        if self.size + length > self.capacity:
-            new_capacity = self.size * 2
-            if new_capacity < self.size + length:
-                new_capacity = (((self.size + length)*2 - 1) // mmap.PAGESIZE + 1) * mmap.PAGESIZE
-            os.truncate(self.filename, new_capacity)
-            self.mmapview = memoryview(mmap.mmap(self.fd, new_capacity))
-            self.capacity = new_capacity
+    def __init__(self, name, file_size=16*1024*1024*1024, **metadata):
+        self.name = name.removesuffix('.safetensors')
+        self.metadata = metadata
+        self.file = self.File(self.name + '.safetensors')
+        self.files = {self.file.filename:self.file}
+        self.file_size = file_size
+        self.total_size = 0
+        self.weight_map = {}
     def add(self, name, tensor):
         print(name, '...')
-        length = tensor.numel() * tensor.dtype.itemsize
-        self._reserve(length)
-        torch.frombuffer(
-                self.mmapview[self.size:self.size+length],
-                dtype=tensor.dtype, count=tensor.numel(),
-        ).view(tensor.shape)[:] = tensor
-        end = self.size + length
-        self.header[name] = {
-            'dtype': 
-                str(tensor.dtype).rsplit('.',1)[-1]
-                    .replace('float','F')
-                    .replace('uint','U')
-                    .replace('int','I')
-                    .removesuffix('fn')
-                    .upper(),
-            'shape':
-                list(tensor.shape),
-            'data_offsets':
-                [self.size, end],
-        }
-        self.size = end
+        self.weight_map[name] = self.file
+        self.file.add(name, tensor)
+        if self.file.size >= self.file_size:
+            self.file.undo(name, tensor)
+            ct = len(self.files)
+            if len(self.files) == 1:
+                self.file.rename(f'{self.name}-{ct:05}.safetensors')
+                self.file.set_metadata(index = str(ct))
+                self.files = {self.file.filename:self.file}
+            self.file.finalize()
+            self.total_size += self.file.size
+            ct += 1
+            self.file = self.File(f'{self.name}-{ct:05}.safetensors', index = ct)
+            self.files[self.file.filename] = self.file
+            self.file.add(name, tensor)
     def finalize(self):
-        print(self.filename, '...')
-        header = json.dumps(self.header, separators=[',',':']).encode()
-        insert = len(header) + 8
-        self._reserve(insert)
-        self.mmapview[insert:insert+self.size] = self.mmapview[:self.size]
-        self.size += insert
-        self.mmapview[:8] = len(header).to_bytes(8, 'little')
-        self.mmapview[8:insert] = header
-        del self.header
-        del self.mmapview
-        os.close(self.fd)
-        os.truncate(self.filename, self.size)
+        self.file.finalize()
+        if len(self.files) > 1:
+            self.total_size += self.file.size
+            index_name = self.name + '.safetensors.index.json'
+            print(index_name, '...')
+            tot = len(self.files)
+            for ct, file in enumerate(self.files.values()):
+                file.rename(f'{self.name}-{ct:05}-of-{tot:06}.safetensors')
+            with open(index_name, 'w') as fh:
+                json.dump({
+                    'metadata': {
+                        **self.metadata,
+                        'total_size': self.total_size,
+                        'weight_map': {
+                            name: file.filename
+                            for name, file in self.weight_map.items()
+                        }
+                    }
+                }, fh)
+        del self.file
+        del self.files
+        del self.metadata
     def delete(self):
-        print('deleting', self.filename, '...')
-        del self.header
-        del self.mmapview
-        os.close(self.fd)
-        os.unlink(self.filename)
+        for file in self.files.values():
+            file.delete()
+        del self.file
+        del self.files
+        del self.metadata
     def __enter__(self):
         return self
     def __exit__(self, Exc, exc, tb):
+        throw = None
         if Exc is None:
-            self.finalize()
+            try:
+                self.finalize()
+            except:
+                self.delete()
+                raise
         else:
             self.delete()
+        
+    class File:
+        def __init__(self, filename, **metadata):
+            self.filename = filename
+            self.fd = os.open(self.filename, os.O_RDWR | os.O_CREAT)
+            self.size = 0
+            self.capacity = 0
+            self.mmapview = None
+            self.header = {'__metadata__': {k:str(v) for k,v in metadata.items()}}
+            self.finalized = False
+        def _reserve(self, length):
+            if self.size + length > self.capacity:
+                new_capacity = self.size * 2
+                if new_capacity < self.size + length:
+                    new_capacity = (((self.size + length)*2 - 1) // mmap.PAGESIZE + 1) * mmap.PAGESIZE
+                os.truncate(self.filename, new_capacity)
+                self.mmapview = memoryview(mmap.mmap(self.fd, new_capacity))
+                self.capacity = new_capacity
+        def add(self, name, tensor):
+            length = tensor.numel() * tensor.dtype.itemsize
+            self._reserve(length)
+            torch.frombuffer(
+                    self.mmapview[self.size:self.size+length],
+                    dtype=tensor.dtype, count=tensor.numel(),
+            ).view(tensor.shape)[:] = tensor
+            end = self.size + length
+            self.header[name] = {
+                'dtype': 
+                    str(tensor.dtype).rsplit('.',1)[-1]
+                        .replace('float','F')
+                        .replace('uint','U')
+                        .replace('int','I')
+                        .removesuffix('fn')
+                        .upper(),
+                'shape':
+                    list(tensor.shape),
+                'data_offsets':
+                    [self.size, end],
+            }
+            self.size = end
+        def undo(self, name, tensor):
+            length = tensor.numel() * tensor.dtype.itemsize
+            del self.header[name]
+            self.size -= length
+        def set_metadata(self, **metadata):
+            m = self.header['__metadata__']
+            for k, v in metadata.items():
+                m[k] = str(v)
+        def rename(self, filename):
+            os.rename(self.filename, filename)
+            self.filename = filename
+            return filename
+        def finalize(self):
+            print(self.filename, '...')
+            header = json.dumps(self.header, separators=[',',':']).encode()
+            insert = len(header) + 8
+            self._reserve(insert)
+            self.mmapview[insert:insert+self.size] = self.mmapview[:self.size]
+            self.size += insert
+            self.mmapview[:8] = len(header).to_bytes(8, 'little')
+            self.mmapview[8:insert] = header
+            del self.header
+            del self.mmapview
+            os.close(self.fd)
+            os.truncate(self.filename, self.size)
+            self.finalized = True
+        def delete(self):
+            if not self.finalized:
+                print('deleting', self.filename, '...')
+                del self.header
+                del self.mmapview
+                os.close(self.fd)
+                self.finalized = True
+            os.unlink(self.filename)