circuitpython/py/qstr.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
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* SPDX-FileCopyrightText: Copyright (c) 2013, 2014 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
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#include <assert.h>
#include <string.h>
#include <stdio.h>
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Introduce a long lived section of the heap. This adapts the allocation process to start from either end of the heap when searching for free space. The default behavior is identical to the existing behavior where it starts with the lowest block and looks higher. Now it can also look from the highest block and lower depending on the long_lived parameter to gc_alloc. As the heap fills, the two sections may overlap. When they overlap, a collect may be triggered in order to keep the long lived section compact. However, free space is always eligable for each type of allocation. By starting from either of the end of the heap we have ability to separate short lived objects from long lived ones. This separation reduces heap fragmentation because long lived objects are easy to densely pack. Most objects are short lived initially but may be made long lived when they are referenced by a type or module. This involves copying the memory and then letting the collect phase free the old portion. QSTR pools and chunks are always long lived because they are never freed. The reallocation, collection and free processes are largely unchanged. They simply also maintain an index to the highest free block as well as the lowest. These indices are used to speed up the allocation search until the next collect. In practice, this change may slightly slow down import statements with the benefit that memory is much less fragmented afterwards. For example, a test import into a 20k heap that leaves ~6k free previously had the largest continuous free space of ~400 bytes. After this change, the largest continuous free space is over 3400 bytes.
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#include "py/gc.h"
#include "py/mpstate.h"
#include "py/qstr.h"
#include "py/gc.h"
#include "py/runtime.h"
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#include "supervisor/linker.h"
// NOTE: we are using linear arrays to store and search for qstr's (unique strings, interned strings)
// ultimately we will replace this with a static hash table of some kind
#if MICROPY_DEBUG_VERBOSE // print debugging info
#define DEBUG_printf DEBUG_printf
#else // don't print debugging info
#define DEBUG_printf(...) (void)0
#endif
// A qstr is an index into the qstr pool.
// The data for a qstr is \0 terminated (so they can be printed using printf)
#define Q_HASH_MASK ((1 << (8 * MICROPY_QSTR_BYTES_IN_HASH)) - 1)
#if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
#define QSTR_ENTER() mp_thread_mutex_lock(&MP_STATE_VM(qstr_mutex), 1)
#define QSTR_EXIT() mp_thread_mutex_unlock(&MP_STATE_VM(qstr_mutex))
#else
#define QSTR_ENTER()
#define QSTR_EXIT()
#endif
// Initial number of entries for qstr pool, set so that the first dynamically
// allocated pool is twice this size. The value here must be <= MP_QSTRnumber_of.
#define MICROPY_ALLOC_QSTR_ENTRIES_INIT (10)
// this must match the equivalent function in makeqstrdata.py
mp_uint_t qstr_compute_hash(const byte *data, size_t len) {
// djb2 algorithm; see http://www.cse.yorku.ca/~oz/hash.html
mp_uint_t hash = 5381;
for (const byte *top = data + len; data < top; data++) {
hash = ((hash << 5) + hash) ^ (*data); // hash * 33 ^ data
}
hash &= Q_HASH_MASK;
// Make sure that valid hash is never zero, zero means "hash not computed"
if (hash == 0) {
hash++;
}
return hash;
}
const qstr_attr_t mp_qstr_const_attr[] = {
#ifndef NO_QSTR
#define QDEF(id, hash, len, str) { hash, len },
#define TRANSLATION(id, length, compressed ...)
#include "genhdr/qstrdefs.generated.h"
#undef TRANSLATION
#undef QDEF
#endif
};
const qstr_pool_t mp_qstr_const_pool = {
NULL, // no previous pool
0, // no previous pool
MICROPY_ALLOC_QSTR_ENTRIES_INIT,
MP_QSTRnumber_of, // corresponds to number of strings in array just below
(qstr_attr_t *)mp_qstr_const_attr,
{
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#ifndef NO_QSTR
#define QDEF(id, hash, len, str) str,
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#define TRANSLATION(id, length, compressed ...)
#include "genhdr/qstrdefs.generated.h"
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#undef TRANSLATION
#undef QDEF
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#endif
},
};
#ifdef MICROPY_QSTR_EXTRA_POOL
extern const qstr_pool_t MICROPY_QSTR_EXTRA_POOL;
#define CONST_POOL MICROPY_QSTR_EXTRA_POOL
#else
#define CONST_POOL mp_qstr_const_pool
#endif
void qstr_init(void) {
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MP_STATE_VM(last_pool) = (qstr_pool_t *)&CONST_POOL; // we won't modify the const_pool since it has no allocated room left
MP_STATE_VM(qstr_last_chunk) = NULL;
#if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
mp_thread_mutex_init(&MP_STATE_VM(qstr_mutex));
#endif
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}
STATIC const char *find_qstr(qstr q, qstr_attr_t *attr) {
// search pool for this qstr
// total_prev_len==0 in the final pool, so the loop will always terminate
const qstr_pool_t *pool = MP_STATE_VM(last_pool);
while (q < pool->total_prev_len) {
pool = pool->prev;
}
q -= pool->total_prev_len;
assert(q < pool->len);
*attr = pool->attrs[q];
return pool->qstrs[q];
}
// qstr_mutex must be taken while in this function
STATIC qstr qstr_add(mp_uint_t hash, mp_uint_t len, const char *q_ptr) {
DEBUG_printf("QSTR: add hash=%d len=%d data=%.*s\n", hash, len, len, q_ptr);
// make sure we have room in the pool for a new qstr
if (MP_STATE_VM(last_pool)->len >= MP_STATE_VM(last_pool)->alloc) {
uint32_t new_pool_length = MP_STATE_VM(last_pool)->alloc * 2;
if (new_pool_length > MICROPY_QSTR_POOL_MAX_ENTRIES) {
new_pool_length = MICROPY_QSTR_POOL_MAX_ENTRIES;
}
#ifdef MICROPY_QSTR_EXTRA_POOL
// Put a lower bound on the allocation size in case the extra qstr pool has few entries
if (new_pool_length < MICROPY_ALLOC_QSTR_ENTRIES_INIT) {
new_pool_length = MICROPY_ALLOC_QSTR_ENTRIES_INIT;
}
#endif
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mp_uint_t pool_size = sizeof(qstr_pool_t)
+ (sizeof(const char *) + sizeof(qstr_attr_t)) * new_pool_length;
qstr_pool_t *pool = (qstr_pool_t *)m_malloc_maybe(pool_size, true);
if (pool == NULL) {
QSTR_EXIT();
m_malloc_fail(new_pool_length);
}
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pool->attrs = (qstr_attr_t *)(pool->qstrs + new_pool_length);
pool->prev = MP_STATE_VM(last_pool);
pool->total_prev_len = MP_STATE_VM(last_pool)->total_prev_len + MP_STATE_VM(last_pool)->len;
pool->alloc = new_pool_length;
pool->len = 0;
MP_STATE_VM(last_pool) = pool;
DEBUG_printf("QSTR: allocate new pool of size %d\n", MP_STATE_VM(last_pool)->alloc);
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}
// add the new qstr
mp_uint_t at = MP_STATE_VM(last_pool)->len;
MP_STATE_VM(last_pool)->attrs[at].hash = hash;
MP_STATE_VM(last_pool)->attrs[at].len = len;
MP_STATE_VM(last_pool)->qstrs[at] = q_ptr;
MP_STATE_VM(last_pool)->len++;
// return id for the newly-added qstr
return MP_STATE_VM(last_pool)->total_prev_len + at;
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}
qstr qstr_find_strn(const char *str, size_t str_len) {
// work out hash of str
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mp_uint_t str_hash = qstr_compute_hash((const byte *)str, str_len);
// search pools for the data
for (const qstr_pool_t *pool = MP_STATE_VM(last_pool); pool != NULL; pool = pool->prev) {
qstr_attr_t *attrs = pool->attrs;
for (mp_uint_t at = 0, top = pool->len; at < top; at++) {
if (attrs[at].hash == str_hash && attrs[at].len == str_len && memcmp(pool->qstrs[at], str, str_len) == 0) {
return pool->total_prev_len + at;
}
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}
}
// not found; return null qstr
return 0;
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}
qstr qstr_from_str(const char *str) {
return qstr_from_strn(str, strlen(str));
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}
qstr qstr_from_strn(const char *str, size_t len) {
QSTR_ENTER();
qstr q = qstr_find_strn(str, len);
if (q == 0) {
// qstr does not exist in interned pool so need to add it
// check that len is not too big
if (len >= (1 << (8 * MICROPY_QSTR_BYTES_IN_LEN))) {
QSTR_EXIT();
mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("Name too long"));
}
// compute number of bytes needed to intern this string
size_t n_bytes = len + 1;
if (MP_STATE_VM(qstr_last_chunk) != NULL && MP_STATE_VM(qstr_last_used) + n_bytes > MP_STATE_VM(qstr_last_alloc)) {
// not enough room at end of previously interned string so try to grow
char *new_p = m_renew_maybe(char, MP_STATE_VM(qstr_last_chunk), MP_STATE_VM(qstr_last_alloc), MP_STATE_VM(qstr_last_alloc) + n_bytes, false);
if (new_p == NULL) {
// could not grow existing memory; shrink it to fit previous
(void)m_renew_maybe(char, MP_STATE_VM(qstr_last_chunk), MP_STATE_VM(qstr_last_alloc), MP_STATE_VM(qstr_last_used), false);
MP_STATE_VM(qstr_last_chunk) = NULL;
} else {
// could grow existing memory
MP_STATE_VM(qstr_last_alloc) += n_bytes;
}
}
if (MP_STATE_VM(qstr_last_chunk) == NULL) {
// no existing memory for the interned string so allocate a new chunk
size_t al = n_bytes;
if (al < MICROPY_ALLOC_QSTR_CHUNK_INIT) {
al = MICROPY_ALLOC_QSTR_CHUNK_INIT;
}
MP_STATE_VM(qstr_last_chunk) = m_new_ll_maybe(char, al);
if (MP_STATE_VM(qstr_last_chunk) == NULL) {
// failed to allocate a large chunk so try with exact size
MP_STATE_VM(qstr_last_chunk) = m_new_ll_maybe(char, n_bytes);
if (MP_STATE_VM(qstr_last_chunk) == NULL) {
QSTR_EXIT();
m_malloc_fail(n_bytes);
}
al = n_bytes;
}
MP_STATE_VM(qstr_last_alloc) = al;
MP_STATE_VM(qstr_last_used) = 0;
}
// allocate memory from the chunk for this new interned string's data
char *q_ptr = MP_STATE_VM(qstr_last_chunk) + MP_STATE_VM(qstr_last_used);
MP_STATE_VM(qstr_last_used) += n_bytes;
// store the interned strings' data
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mp_uint_t hash = qstr_compute_hash((const byte *)str, len);
memcpy(q_ptr, str, len);
q_ptr[len] = '\0';
q = qstr_add(hash, len, q_ptr);
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}
QSTR_EXIT();
return q;
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}
mp_uint_t PLACE_IN_ITCM(qstr_hash)(qstr q) {
qstr_attr_t attr;
find_qstr(q, &attr);
return attr.hash;
}
size_t qstr_len(qstr q) {
qstr_attr_t attr;
find_qstr(q, &attr);
return attr.len;
}
const char *qstr_str(qstr q) {
qstr_attr_t attr;
return find_qstr(q, &attr);
}
const byte *qstr_data(qstr q, size_t *len) {
qstr_attr_t attr;
const char *qd = find_qstr(q, &attr);
*len = attr.len;
return (byte *)qd;
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}
void qstr_pool_info(size_t *n_pool, size_t *n_qstr, size_t *n_str_data_bytes, size_t *n_total_bytes) {
QSTR_ENTER();
*n_pool = 0;
*n_qstr = 0;
*n_str_data_bytes = 0;
*n_total_bytes = 0;
for (const qstr_pool_t *pool = MP_STATE_VM(last_pool); pool != NULL && pool != &CONST_POOL; pool = pool->prev) {
*n_pool += 1;
*n_qstr += pool->len;
for (const qstr_attr_t *q = pool->attrs, *q_top = pool->attrs + pool->len; q < q_top; q++) {
*n_str_data_bytes += sizeof(*q) + q->len + 1;
}
#if MICROPY_ENABLE_GC
// this counts actual bytes used in heap
*n_total_bytes += gc_nbytes(pool) - sizeof(qstr_attr_t) * pool->alloc;
#else
*n_total_bytes += sizeof(qstr_pool_t) + sizeof(const char *) * pool->alloc;
#endif
}
*n_total_bytes += *n_str_data_bytes;
QSTR_EXIT();
}
#if MICROPY_PY_MICROPYTHON_MEM_INFO
void qstr_dump_data(void) {
QSTR_ENTER();
for (const qstr_pool_t *pool = MP_STATE_VM(last_pool); pool != NULL && pool != &CONST_POOL; pool = pool->prev) {
for (const char *const *q = pool->qstrs, *const *q_top = pool->qstrs + pool->len; q < q_top; q++) {
mp_printf(&mp_plat_print, "Q(%s)\n", *q);
}
}
QSTR_EXIT();
}
#endif