wehub-resource-sync
98 lines
3.8 KiB
ReStructuredText
98 lines
3.8 KiB
ReStructuredText
.. Licensed to the Apache Software Foundation (ASF) under one
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or more contributor license agreements. See the NOTICE file
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distributed with this work for additional information
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regarding copyright ownership. The ASF licenses this file
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to you under the Apache License, Version 2.0 (the
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"License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License at
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.. http://www.apache.org/licenses/LICENSE-2.0
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.. Unless required by applicable law or agreed to in writing,
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software distributed under the License is distributed on an
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"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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KIND, either express or implied. See the License for the
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specific language governing permissions and limitations
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under the License.
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.. _error-handling-guide:
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Error Handling Guide
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====================
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.. contents::
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:depth: 2
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:local:
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TVM contains structured error classes to indicate specific types of error.
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Please raise a specific error type when possible, so that users can
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write code to handle a specific error category if necessary.
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You can directly raise the specific error object in python.
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In other languages like c++, you simply add ``<ErrorType>:`` prefix to
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the error message(see below).
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.. note::
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Please refer to :py:mod:`tvm.error` for the list of errors.
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Raise a Specific Error in C++
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-----------------------------
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You can add ``<ErrorType>:`` prefix to your error message to
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raise an error of the corresponding type.
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Note that you do not have to add a new type
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:py:class:`tvm.error.InternalError` will be raised by default when
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there is no error type prefix in the message.
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This mechanism works for both ``LOG(FATAL)`` and ``TVM_FFI_ICHECK`` macros.
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The following code gives an example on how to do so.
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.. code:: c
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// src/api_test.cc
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void ErrorTest(int x, int y) {
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TVM_FFI_ICHECK_EQ(x, y) << "ValueError: expect x and y to be equal."
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if (x == 1) {
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LOG(FATAL) << "InternalError: cannot reach here";
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}
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}
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When a C++ function registered via the FFI raises an error with a typed prefix,
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the TVM FFI system will automatically map it to the corresponding Python exception
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class. For example, a ``ValueError:`` prefix in the error message will raise a Python
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``ValueError``, and an ``InternalError:`` prefix will raise ``tvm.error.InternalError``.
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TVM's FFI system combines both the Python and C++ stacktraces into a single message,
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and generates the corresponding error class automatically.
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How to choose an Error Type
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---------------------------
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You can go through the error types are listed below, try to use common
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sense and also refer to the choices in the existing code.
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We try to keep a reasonable amount of error types.
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If you feel there is a need to add a new error type, do the following steps:
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- Send a RFC proposal with a description and usage examples in the current codebase.
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- Add the new error type to :py:mod:`tvm.error` with clear documents.
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- Update the list in this file to include the new error type.
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- Change the code to use the new error type.
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We also recommend to use less abstraction when creating the short error messages.
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The code is more readable in this way, and also opens path to craft specific
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error messages when necessary.
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.. code:: python
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def preferred():
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# Very clear about what is being raised and what is the error message.
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raise OpNotImplemented("Operator relu is not implemented in the ONNX frontend")
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def _op_not_implemented(op_name):
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return OpNotImplemented("Operator {} is not implemented.").format(op_name)
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def not_preferred():
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# Introduces another level of indirection.
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raise _op_not_implemented("relu")
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If we need to introduce a wrapper function that constructs multi-line error messages,
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please put wrapper in the same file so other developers can look up the implementation easily.
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