view contrib/python-zstandard/c-ext/compressionchunker.c @ 45087:83f75f1efdcc

overlayworkingctx: rename misleadingly named `isempty()` method

This method is only about whether there are file changes, not about whether the
commit will be empty or not.

One user of the method was incorrectly assuming the latter meaning, leading to
the bug for which a test case was added in D8727. I’ve added a FIXME to the
code.

The original motivation for the rename was that I want to add
`committablectx.isempty()`, that properly checks if a commit will be empty,
using the exact same logic as in `repo.commit()`, and I wanted to avoid a name
clash.

Differential Revision: https://phab.mercurial-scm.org/D8728

/**
* Copyright (c) 2018-present, Gregory Szorc
* All rights reserved.
*
* This software may be modified and distributed under the terms
* of the BSD license. See the LICENSE file for details.
*/

#include "python-zstandard.h"

extern PyObject* ZstdError;

PyDoc_STRVAR(ZstdCompressionChunkerIterator__doc__,
	"Iterator of output chunks from ZstdCompressionChunker.\n"
);

static void ZstdCompressionChunkerIterator_dealloc(ZstdCompressionChunkerIterator* self) {
	Py_XDECREF(self->chunker);

	PyObject_Del(self);
}

static PyObject* ZstdCompressionChunkerIterator_iter(PyObject* self) {
	Py_INCREF(self);
	return self;
}

static PyObject* ZstdCompressionChunkerIterator_iternext(ZstdCompressionChunkerIterator* self) {
	size_t zresult;
	PyObject* chunk;
	ZstdCompressionChunker* chunker = self->chunker;
	ZSTD_EndDirective zFlushMode;

	if (self->mode != compressionchunker_mode_normal && chunker->input.pos != chunker->input.size) {
		PyErr_SetString(ZstdError, "input should have been fully consumed before calling flush() or finish()");
		return NULL;
	}

	if (chunker->finished) {
		return NULL;
	}

	/* If we have data left in the input, consume it. */
	while (chunker->input.pos < chunker->input.size) {
		Py_BEGIN_ALLOW_THREADS
		zresult = ZSTD_compressStream2(chunker->compressor->cctx, &chunker->output,
			&chunker->input, ZSTD_e_continue);
		Py_END_ALLOW_THREADS

		/* Input is fully consumed. */
		if (chunker->input.pos == chunker->input.size) {
			chunker->input.src = NULL;
			chunker->input.pos = 0;
			chunker->input.size = 0;
			PyBuffer_Release(&chunker->inBuffer);
		}

		if (ZSTD_isError(zresult)) {
			PyErr_Format(ZstdError, "zstd compress error: %s", ZSTD_getErrorName(zresult));
			return NULL;
		}

		/* If it produced a full output chunk, emit it. */
		if (chunker->output.pos == chunker->output.size) {
			chunk = PyBytes_FromStringAndSize(chunker->output.dst, chunker->output.pos);
			if (!chunk) {
				return NULL;
			}

			chunker->output.pos = 0;

			return chunk;
		}

		/* Else continue to compress available input data. */
	}

	/* We also need this here for the special case of an empty input buffer. */
	if (chunker->input.pos == chunker->input.size) {
		chunker->input.src = NULL;
		chunker->input.pos = 0;
		chunker->input.size = 0;
		PyBuffer_Release(&chunker->inBuffer);
	}

	/* No more input data. A partial chunk may be in chunker->output.
	 * If we're in normal compression mode, we're done. Otherwise if we're in
	 * flush or finish mode, we need to emit what data remains.
	 */
	if (self->mode == compressionchunker_mode_normal) {
		/* We don't need to set StopIteration. */
		return NULL;
	}

	if (self->mode == compressionchunker_mode_flush) {
		zFlushMode = ZSTD_e_flush;
	}
	else if (self->mode == compressionchunker_mode_finish) {
		zFlushMode = ZSTD_e_end;
	}
	else {
		PyErr_SetString(ZstdError, "unhandled compression mode; this should never happen");
		return NULL;
	}

	Py_BEGIN_ALLOW_THREADS
	zresult = ZSTD_compressStream2(chunker->compressor->cctx, &chunker->output,
		&chunker->input, zFlushMode);
	Py_END_ALLOW_THREADS

	if (ZSTD_isError(zresult)) {
		PyErr_Format(ZstdError, "zstd compress error: %s",
			ZSTD_getErrorName(zresult));
		return NULL;
	}

	if (!zresult && chunker->output.pos == 0) {
		return NULL;
	}

	chunk = PyBytes_FromStringAndSize(chunker->output.dst, chunker->output.pos);
	if (!chunk) {
		return NULL;
	}

	chunker->output.pos = 0;

	if (!zresult && self->mode == compressionchunker_mode_finish) {
		chunker->finished = 1;
	}

	return chunk;
}

PyTypeObject ZstdCompressionChunkerIteratorType = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"zstd.ZstdCompressionChunkerIterator", /* tp_name */
	sizeof(ZstdCompressionChunkerIterator), /* tp_basicsize */
	0,                               /* tp_itemsize */
	(destructor)ZstdCompressionChunkerIterator_dealloc, /* tp_dealloc */
	0,                               /* tp_print */
	0,                               /* tp_getattr */
	0,                               /* tp_setattr */
	0,                               /* tp_compare */
	0,                               /* tp_repr */
	0,                               /* tp_as_number */
	0,                               /* tp_as_sequence */
	0,                               /* tp_as_mapping */
	0,                               /* tp_hash */
	0,                               /* tp_call */
	0,                               /* tp_str */
	0,                               /* tp_getattro */
	0,                               /* tp_setattro */
	0,                               /* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
	ZstdCompressionChunkerIterator__doc__, /* tp_doc */
	0,                               /* tp_traverse */
	0,                               /* tp_clear */
	0,                               /* tp_richcompare */
	0,                               /* tp_weaklistoffset */
	ZstdCompressionChunkerIterator_iter, /* tp_iter */
	(iternextfunc)ZstdCompressionChunkerIterator_iternext, /* tp_iternext */
	0,                               /* tp_methods */
	0,                               /* tp_members */
	0,                               /* tp_getset */
	0,                               /* tp_base */
	0,                               /* tp_dict */
	0,                               /* tp_descr_get */
	0,                               /* tp_descr_set */
	0,                               /* tp_dictoffset */
	0,                               /* tp_init */
	0,                               /* tp_alloc */
	PyType_GenericNew,              /* tp_new */
};

PyDoc_STRVAR(ZstdCompressionChunker__doc__,
	"Compress chunks iteratively into exact chunk sizes.\n"
);

static void ZstdCompressionChunker_dealloc(ZstdCompressionChunker* self) {
	PyBuffer_Release(&self->inBuffer);
	self->input.src = NULL;

	PyMem_Free(self->output.dst);
	self->output.dst = NULL;

	Py_XDECREF(self->compressor);

	PyObject_Del(self);
}

static ZstdCompressionChunkerIterator* ZstdCompressionChunker_compress(ZstdCompressionChunker* self, PyObject* args, PyObject* kwargs) {
	static char* kwlist[] = {
		"data",
		NULL
	};

	ZstdCompressionChunkerIterator* result;

	if (self->finished) {
		PyErr_SetString(ZstdError, "cannot call compress() after compression finished");
		return NULL;
	}

	if (self->inBuffer.obj) {
		PyErr_SetString(ZstdError,
			"cannot perform operation before consuming output from previous operation");
		return NULL;
	}

#if PY_MAJOR_VERSION >= 3
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "y*:compress",
#else
	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "s*:compress",
#endif
		kwlist, &self->inBuffer)) {
		return NULL;
	}

	if (!PyBuffer_IsContiguous(&self->inBuffer, 'C') || self->inBuffer.ndim > 1) {
		PyErr_SetString(PyExc_ValueError,
			"data buffer should be contiguous and have at most one dimension");
		PyBuffer_Release(&self->inBuffer);
		return NULL;
	}

	result = (ZstdCompressionChunkerIterator*)PyObject_CallObject((PyObject*)&ZstdCompressionChunkerIteratorType, NULL);
	if (!result) {
		PyBuffer_Release(&self->inBuffer);
		return NULL;
	}

	self->input.src = self->inBuffer.buf;
	self->input.size = self->inBuffer.len;
	self->input.pos = 0;

	result->chunker = self;
	Py_INCREF(result->chunker);

	result->mode = compressionchunker_mode_normal;

	return result;
}

static ZstdCompressionChunkerIterator* ZstdCompressionChunker_finish(ZstdCompressionChunker* self) {
	ZstdCompressionChunkerIterator* result;

	if (self->finished) {
		PyErr_SetString(ZstdError, "cannot call finish() after compression finished");
		return NULL;
	}

	if (self->inBuffer.obj) {
		PyErr_SetString(ZstdError,
			"cannot call finish() before consuming output from previous operation");
		return NULL;
	}

	result = (ZstdCompressionChunkerIterator*)PyObject_CallObject((PyObject*)&ZstdCompressionChunkerIteratorType, NULL);
	if (!result) {
		return NULL;
	}

	result->chunker = self;
	Py_INCREF(result->chunker);

	result->mode = compressionchunker_mode_finish;

	return result;
}

static ZstdCompressionChunkerIterator* ZstdCompressionChunker_flush(ZstdCompressionChunker* self, PyObject* args, PyObject* kwargs) {
	ZstdCompressionChunkerIterator* result;

	if (self->finished) {
		PyErr_SetString(ZstdError, "cannot call flush() after compression finished");
		return NULL;
	}

	if (self->inBuffer.obj) {
		PyErr_SetString(ZstdError,
			"cannot call flush() before consuming output from previous operation");
		return NULL;
	}

	result = (ZstdCompressionChunkerIterator*)PyObject_CallObject((PyObject*)&ZstdCompressionChunkerIteratorType, NULL);
	if (!result) {
		return NULL;
	}

	result->chunker = self;
	Py_INCREF(result->chunker);

	result->mode = compressionchunker_mode_flush;

	return result;
}

static PyMethodDef ZstdCompressionChunker_methods[] = {
	{ "compress", (PyCFunction)ZstdCompressionChunker_compress, METH_VARARGS | METH_KEYWORDS,
	PyDoc_STR("compress data") },
	{ "finish", (PyCFunction)ZstdCompressionChunker_finish, METH_NOARGS,
	PyDoc_STR("finish compression operation") },
	{ "flush", (PyCFunction)ZstdCompressionChunker_flush, METH_VARARGS | METH_KEYWORDS,
	PyDoc_STR("finish compression operation") },
	{ NULL, NULL }
};

PyTypeObject ZstdCompressionChunkerType = {
	PyVarObject_HEAD_INIT(NULL, 0)
	"zstd.ZstdCompressionChunkerType",  /* tp_name */
	sizeof(ZstdCompressionChunker),     /* tp_basicsize */
	0,                                  /* tp_itemsize */
	(destructor)ZstdCompressionChunker_dealloc, /* tp_dealloc */
	0,                                  /* tp_print */
	0,                                  /* tp_getattr */
	0,                                  /* tp_setattr */
	0,                                  /* tp_compare */
	0,                                  /* tp_repr */
	0,                                  /* tp_as_number */
	0,                                  /* tp_as_sequence */
	0,                                  /* tp_as_mapping */
	0,                                  /* tp_hash */
	0,                                  /* tp_call */
	0,                                  /* tp_str */
	0,                                  /* tp_getattro */
	0,                                  /* tp_setattro */
	0,                                  /* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
	ZstdCompressionChunker__doc__,      /* tp_doc */
	0,                                  /* tp_traverse */
	0,                                  /* tp_clear */
	0,                                  /* tp_richcompare */
	0,                                  /* tp_weaklistoffset */
	0,                                  /* tp_iter */
	0,                                  /* tp_iternext */
	ZstdCompressionChunker_methods,     /* tp_methods */
	0,                                  /* tp_members */
	0,                                  /* tp_getset */
	0,                                  /* tp_base */
	0,                                  /* tp_dict */
	0,                                  /* tp_descr_get */
	0,                                  /* tp_descr_set */
	0,                                  /* tp_dictoffset */
	0,                                  /* tp_init */
	0,                                  /* tp_alloc */
	PyType_GenericNew,                  /* tp_new */
};

void compressionchunker_module_init(PyObject* module) {
	Py_TYPE(&ZstdCompressionChunkerIteratorType) = &PyType_Type;
	if (PyType_Ready(&ZstdCompressionChunkerIteratorType) < 0) {
		return;
	}

	Py_TYPE(&ZstdCompressionChunkerType) = &PyType_Type;
	if (PyType_Ready(&ZstdCompressionChunkerType) < 0) {
		return;
	}
}