The semantics of the list visit are somewhat baroque, with the following pseudocode when FooList is used: start() for (prev = head; cur = next(prev); prev = &cur) { visit(&cur->value) } Note that these semantics (advance before visit) requires that the first call to next() return the list head, while all other calls return the next element of the list; that is, every visitor implementation is required to track extra state to decide whether to return the input as-is, or to advance. It also requires an argument of 'GenericList **' to next(), solely because the first iteration might need to modify the caller's GenericList head, so that all other calls have to do a layer of dereferencing. Thankfully, we only have two uses of list visits in the entire code base: one in spapr_drc (which completely avoids visit_next_list(), feeding in integers from a different source than uint8List), and one in qapi-visit.py. That is, all other list visitors are generated in qapi-visit.c, and share the same paradigm based on a qapi FooList type, so we can refactor how lists are laid out with minimal churn among clients. We can greatly simplify things by hoisting the special case into the start() routine, and flipping the order in the loop to visit before advance: start(head) for (tail = *head; tail; tail = next(tail)) { visit(&tail->value) } With the simpler semantics, visitors have less state to track, the argument to next() is reduced to 'GenericList *', and it also becomes obvious whether an input visitor is allocating a FooList during visit_start_list() (rather than the old way of not knowing if an allocation happened until the first visit_next_list()). As a minor drawback, we now allocate in two functions instead of one, and have to pass the size to both functions (unless we were to tweak the input visitors to cache the size to start_list for reuse during next_list, but that defeats the goal of less visitor state). The signature of visit_start_list() is chosen to match visit_start_struct(), with the new parameters after 'name'. The spapr_drc case is a virtual visit, done by passing NULL for list, similarly to how NULL is passed to visit_start_struct() when a qapi type is not used in those visits. It was easy to provide these semantics for qmp-output and dealloc visitors, and a bit harder for qmp-input (several prerequisite patches refactored things to make this patch straightforward). But it turned out that the string and opts visitors munge enough other state during visit_next_list() to make it easier to just document and require a GenericList visit for now; an assertion will remind us to adjust things if we need the semantics in the future. Several pre-requisite cleanup patches made the reshuffling of the various visitors easier; particularly the qmp input visitor. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1461879932-9020-24-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
354 lines
9.9 KiB
C
354 lines
9.9 KiB
C
/*
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* String printing Visitor
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*
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* Copyright Red Hat, Inc. 2012-2016
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*
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* Author: Paolo Bonzini <pbonzini@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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*/
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#include "qemu/osdep.h"
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#include "qemu-common.h"
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#include "qapi/string-output-visitor.h"
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#include "qapi/visitor-impl.h"
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#include "qemu/host-utils.h"
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#include <math.h>
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#include "qemu/range.h"
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enum ListMode {
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LM_NONE, /* not traversing a list of repeated options */
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LM_STARTED, /* next_list() ready to be called */
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LM_IN_PROGRESS, /* next_list() has been called.
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*
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* Generating the next list link will consume the most
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* recently parsed QemuOpt instance of the repeated
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* option.
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*
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* Parsing a value into the list link will examine the
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* next QemuOpt instance of the repeated option, and
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* possibly enter LM_SIGNED_INTERVAL or
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* LM_UNSIGNED_INTERVAL.
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*/
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LM_SIGNED_INTERVAL, /* next_list() has been called.
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*
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* Generating the next list link will consume the most
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* recently stored element from the signed interval,
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* parsed from the most recent QemuOpt instance of the
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* repeated option. This may consume QemuOpt itself
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* and return to LM_IN_PROGRESS.
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*
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* Parsing a value into the list link will store the
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* next element of the signed interval.
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*/
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LM_UNSIGNED_INTERVAL,/* Same as above, only for an unsigned interval. */
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LM_END, /* next_list() called, about to see last element. */
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};
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typedef enum ListMode ListMode;
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struct StringOutputVisitor
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{
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Visitor visitor;
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bool human;
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GString *string;
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ListMode list_mode;
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union {
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int64_t s;
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uint64_t u;
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} range_start, range_end;
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GList *ranges;
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};
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static StringOutputVisitor *to_sov(Visitor *v)
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{
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return container_of(v, StringOutputVisitor, visitor);
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}
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static void string_output_set(StringOutputVisitor *sov, char *string)
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{
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if (sov->string) {
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g_string_free(sov->string, true);
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}
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sov->string = g_string_new(string);
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g_free(string);
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}
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static void string_output_append(StringOutputVisitor *sov, int64_t a)
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{
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Range *r = g_malloc0(sizeof(*r));
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r->begin = a;
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r->end = a + 1;
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sov->ranges = g_list_insert_sorted_merged(sov->ranges, r, range_compare);
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}
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static void string_output_append_range(StringOutputVisitor *sov,
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int64_t s, int64_t e)
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{
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Range *r = g_malloc0(sizeof(*r));
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r->begin = s;
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r->end = e + 1;
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sov->ranges = g_list_insert_sorted_merged(sov->ranges, r, range_compare);
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}
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static void format_string(StringOutputVisitor *sov, Range *r, bool next,
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bool human)
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{
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if (r->end - r->begin > 1) {
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if (human) {
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g_string_append_printf(sov->string, "0x%" PRIx64 "-0x%" PRIx64,
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r->begin, r->end - 1);
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} else {
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g_string_append_printf(sov->string, "%" PRId64 "-%" PRId64,
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r->begin, r->end - 1);
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}
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} else {
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if (human) {
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g_string_append_printf(sov->string, "0x%" PRIx64, r->begin);
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} else {
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g_string_append_printf(sov->string, "%" PRId64, r->begin);
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}
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}
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if (next) {
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g_string_append(sov->string, ",");
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}
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}
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static void print_type_int64(Visitor *v, const char *name, int64_t *obj,
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Error **errp)
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{
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StringOutputVisitor *sov = to_sov(v);
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GList *l;
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switch (sov->list_mode) {
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case LM_NONE:
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string_output_append(sov, *obj);
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break;
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case LM_STARTED:
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sov->range_start.s = *obj;
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sov->range_end.s = *obj;
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sov->list_mode = LM_IN_PROGRESS;
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return;
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case LM_IN_PROGRESS:
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if (sov->range_end.s + 1 == *obj) {
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sov->range_end.s++;
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} else {
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if (sov->range_start.s == sov->range_end.s) {
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string_output_append(sov, sov->range_end.s);
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} else {
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assert(sov->range_start.s < sov->range_end.s);
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string_output_append_range(sov, sov->range_start.s,
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sov->range_end.s);
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}
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sov->range_start.s = *obj;
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sov->range_end.s = *obj;
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}
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return;
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case LM_END:
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if (sov->range_end.s + 1 == *obj) {
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sov->range_end.s++;
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assert(sov->range_start.s < sov->range_end.s);
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string_output_append_range(sov, sov->range_start.s,
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sov->range_end.s);
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} else {
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if (sov->range_start.s == sov->range_end.s) {
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string_output_append(sov, sov->range_end.s);
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} else {
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assert(sov->range_start.s < sov->range_end.s);
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string_output_append_range(sov, sov->range_start.s,
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sov->range_end.s);
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}
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string_output_append(sov, *obj);
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}
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break;
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default:
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abort();
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}
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l = sov->ranges;
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while (l) {
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Range *r = l->data;
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format_string(sov, r, l->next != NULL, false);
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l = l->next;
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}
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if (sov->human) {
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l = sov->ranges;
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g_string_append(sov->string, " (");
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while (l) {
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Range *r = l->data;
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format_string(sov, r, l->next != NULL, true);
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l = l->next;
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}
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g_string_append(sov->string, ")");
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}
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}
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static void print_type_uint64(Visitor *v, const char *name, uint64_t *obj,
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Error **errp)
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{
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/* FIXME: print_type_int64 mishandles values over INT64_MAX */
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int64_t i = *obj;
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print_type_int64(v, name, &i, errp);
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}
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static void print_type_size(Visitor *v, const char *name, uint64_t *obj,
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Error **errp)
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{
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StringOutputVisitor *sov = to_sov(v);
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static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T', 'P', 'E' };
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uint64_t div, val;
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char *out;
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int i;
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if (!sov->human) {
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out = g_strdup_printf("%"PRIu64, *obj);
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string_output_set(sov, out);
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return;
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}
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val = *obj;
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/* The exponent (returned in i) minus one gives us
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* floor(log2(val * 1024 / 1000). The correction makes us
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* switch to the higher power when the integer part is >= 1000.
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*/
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frexp(val / (1000.0 / 1024.0), &i);
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i = (i - 1) / 10;
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assert(i < ARRAY_SIZE(suffixes));
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div = 1ULL << (i * 10);
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out = g_strdup_printf("%"PRIu64" (%0.3g %c%s)", val,
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(double)val/div, suffixes[i], i ? "iB" : "");
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string_output_set(sov, out);
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}
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static void print_type_bool(Visitor *v, const char *name, bool *obj,
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Error **errp)
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{
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StringOutputVisitor *sov = to_sov(v);
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string_output_set(sov, g_strdup(*obj ? "true" : "false"));
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}
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static void print_type_str(Visitor *v, const char *name, char **obj,
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Error **errp)
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{
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StringOutputVisitor *sov = to_sov(v);
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char *out;
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if (sov->human) {
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out = *obj ? g_strdup_printf("\"%s\"", *obj) : g_strdup("<null>");
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} else {
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out = g_strdup(*obj ? *obj : "");
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}
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string_output_set(sov, out);
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}
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static void print_type_number(Visitor *v, const char *name, double *obj,
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Error **errp)
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{
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StringOutputVisitor *sov = to_sov(v);
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string_output_set(sov, g_strdup_printf("%f", *obj));
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}
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static void
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start_list(Visitor *v, const char *name, GenericList **list, size_t size,
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Error **errp)
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{
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StringOutputVisitor *sov = to_sov(v);
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/* we can't traverse a list in a list */
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assert(sov->list_mode == LM_NONE);
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/* We don't support visits without a list */
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assert(list);
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/* List handling is only needed if there are at least two elements */
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if (*list && (*list)->next) {
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sov->list_mode = LM_STARTED;
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}
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}
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static GenericList *next_list(Visitor *v, GenericList *tail, size_t size)
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{
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StringOutputVisitor *sov = to_sov(v);
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GenericList *ret = tail->next;
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if (ret && !ret->next) {
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sov->list_mode = LM_END;
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}
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return ret;
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}
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static void end_list(Visitor *v)
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{
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StringOutputVisitor *sov = to_sov(v);
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assert(sov->list_mode == LM_STARTED ||
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sov->list_mode == LM_END ||
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sov->list_mode == LM_NONE ||
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sov->list_mode == LM_IN_PROGRESS);
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sov->list_mode = LM_NONE;
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}
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char *string_output_get_string(StringOutputVisitor *sov)
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{
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char *string = g_string_free(sov->string, false);
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sov->string = NULL;
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return string;
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}
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Visitor *string_output_get_visitor(StringOutputVisitor *sov)
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{
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return &sov->visitor;
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}
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static void free_range(void *range, void *dummy)
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{
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g_free(range);
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}
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void string_output_visitor_cleanup(StringOutputVisitor *sov)
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{
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if (sov->string) {
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g_string_free(sov->string, true);
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}
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g_list_foreach(sov->ranges, free_range, NULL);
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g_list_free(sov->ranges);
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g_free(sov);
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}
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StringOutputVisitor *string_output_visitor_new(bool human)
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{
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StringOutputVisitor *v;
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v = g_malloc0(sizeof(*v));
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v->string = g_string_new(NULL);
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v->human = human;
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v->visitor.type = VISITOR_OUTPUT;
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v->visitor.type_int64 = print_type_int64;
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v->visitor.type_uint64 = print_type_uint64;
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v->visitor.type_size = print_type_size;
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v->visitor.type_bool = print_type_bool;
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v->visitor.type_str = print_type_str;
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v->visitor.type_number = print_type_number;
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v->visitor.start_list = start_list;
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v->visitor.next_list = next_list;
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v->visitor.end_list = end_list;
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return v;
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}
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