55e1819c50
The QObject hierarchy is small enough, and unlikely to grow further (since we only use it to map to JSON and already cover all JSON types), that we can simplify things by not tracking a separate vtable, but just inline the code element of the vtable QType directly into QObject (renamed to type), and track a separate array of destroy functions. We can drop qnull_destroy_obj() in the process. The remaining QObject subclasses must export their destructor. This also has the nice benefit of moving the typename 'QType' out of the way, so that the next patch can repurpose it for a nicer name for 'qtype_code'. The various objects are still the same size (so no change in cache line pressure), but now have less indirection (although I didn't bother benchmarking to see if there is a noticeable speedup, as we don't have hard evidence that this was in a performance hotspot in the first place). A future patch could drop the refcnt size to 32 bits for a smaller struct on 64-bit architectures, if desired (we have limits on the largest JSON that we are willing to parse, and will probably never need to take full advantage of a 64-bit refcnt). Suggested-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1449033659-25497-2-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
143 lines
3.1 KiB
C
143 lines
3.1 KiB
C
/*
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* QString Module
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*
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* Copyright (C) 2009 Red Hat Inc.
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*
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* Authors:
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* Luiz Capitulino <lcapitulino@redhat.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*/
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#include "qapi/qmp/qobject.h"
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#include "qapi/qmp/qstring.h"
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#include "qemu-common.h"
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/**
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* qstring_new(): Create a new empty QString
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*
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* Return strong reference.
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*/
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QString *qstring_new(void)
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{
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return qstring_from_str("");
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}
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/**
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* qstring_get_length(): Get the length of a QString
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*/
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size_t qstring_get_length(const QString *qstring)
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{
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return qstring->length;
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}
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/**
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* qstring_from_substr(): Create a new QString from a C string substring
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*
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* Return string reference
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*/
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QString *qstring_from_substr(const char *str, int start, int end)
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{
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QString *qstring;
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qstring = g_malloc(sizeof(*qstring));
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qobject_init(QOBJECT(qstring), QTYPE_QSTRING);
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qstring->length = end - start + 1;
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qstring->capacity = qstring->length;
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qstring->string = g_malloc(qstring->capacity + 1);
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memcpy(qstring->string, str + start, qstring->length);
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qstring->string[qstring->length] = 0;
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return qstring;
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}
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/**
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* qstring_from_str(): Create a new QString from a regular C string
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*
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* Return strong reference.
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*/
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QString *qstring_from_str(const char *str)
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{
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return qstring_from_substr(str, 0, strlen(str) - 1);
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}
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static void capacity_increase(QString *qstring, size_t len)
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{
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if (qstring->capacity < (qstring->length + len)) {
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qstring->capacity += len;
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qstring->capacity *= 2; /* use exponential growth */
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qstring->string = g_realloc(qstring->string, qstring->capacity + 1);
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}
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}
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/* qstring_append(): Append a C string to a QString
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*/
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void qstring_append(QString *qstring, const char *str)
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{
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size_t len = strlen(str);
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capacity_increase(qstring, len);
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memcpy(qstring->string + qstring->length, str, len);
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qstring->length += len;
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qstring->string[qstring->length] = 0;
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}
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void qstring_append_int(QString *qstring, int64_t value)
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{
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char num[32];
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snprintf(num, sizeof(num), "%" PRId64, value);
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qstring_append(qstring, num);
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}
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/**
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* qstring_append_chr(): Append a C char to a QString
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*/
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void qstring_append_chr(QString *qstring, int c)
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{
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capacity_increase(qstring, 1);
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qstring->string[qstring->length++] = c;
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qstring->string[qstring->length] = 0;
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}
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/**
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* qobject_to_qstring(): Convert a QObject to a QString
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*/
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QString *qobject_to_qstring(const QObject *obj)
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{
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if (!obj || qobject_type(obj) != QTYPE_QSTRING) {
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return NULL;
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}
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return container_of(obj, QString, base);
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}
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/**
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* qstring_get_str(): Return a pointer to the stored string
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*
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* NOTE: Should be used with caution, if the object is deallocated
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* this pointer becomes invalid.
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*/
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const char *qstring_get_str(const QString *qstring)
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{
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return qstring->string;
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}
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/**
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* qstring_destroy_obj(): Free all memory allocated by a QString
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* object
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*/
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void qstring_destroy_obj(QObject *obj)
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{
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QString *qs;
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assert(obj != NULL);
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qs = qobject_to_qstring(obj);
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g_free(qs->string);
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g_free(qs);
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}
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