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transactions: Amend pending transactions

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The transaction system contains a necessary optimization where a popped
transaction is combined with later, similar transactions. This breaks
the chronological order of states, and can lead to desynchronized
geometries.

To fix this, we replace the queue with only 2 transactions: current and
pending. If a pending transaction exists, it is updated with new state
instead of creating additional transactions.

As we never have more than a single waiting transaction, we no longer
need the queue optimization that is causing problems.

Closes: https://github.com/swaywm/sway/issues/6012
This commit is contained in:
Kenny Levinsen 2021-02-12 21:27:28 +01:00 committed by Simon Ser
parent b944735b47
commit c8bf84c82d
3 changed files with 93 additions and 85 deletions
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18
include/sway/server.h
View file

@ -23,6 +23,8 @@
#include "sway/xwayland.h"
#endif
struct sway_transaction;
struct sway_server {
struct wl_display *wl_display;
struct wl_event_loop *wl_event_loop;
@ -85,8 +87,22 @@ struct sway_server {
struct wlr_text_input_manager_v3 *text_input;
struct wlr_foreign_toplevel_manager_v1 *foreign_toplevel_manager;
// The timeout for transactions, after which a transaction is applied
// regardless of readiness.
size_t txn_timeout_ms;
list_t *transactions;
// Stores a transaction after it has been committed, but is waiting for
// views to ack the new dimensions before being applied. A queued
// transaction is frozen and must not have new instructions added to it.
struct sway_transaction *queued_transaction;
// Stores a pending transaction that will be committed once the existing
// queued transaction is applied and freed. The pending transaction can be
// updated with new instructions as needed.
struct sway_transaction *pending_transaction;
// Stores the nodes that have been marked as "dirty" and will be put into
// the pending transaction.
list_t *dirty_nodes;
};

158
sway/desktop/transaction.c
View file

@ -87,7 +87,11 @@ static void transaction_destroy(struct sway_transaction *transaction) {
static void copy_output_state(struct sway_output *output,
struct sway_transaction_instruction *instruction) {
struct sway_output_state *state = &instruction->output_state;
state->workspaces = create_list();
if (state->workspaces) {
state->workspaces->length = 0;
} else {
state->workspaces = create_list();
}
list_cat(state->workspaces, output->workspaces);
state->active_workspace = output_get_active_workspace(output);
@ -105,8 +109,16 @@ static void copy_workspace_state(struct sway_workspace *ws,
state->layout = ws->layout;
state->output = ws->output;
state->floating = create_list();
state->tiling = create_list();
if (state->floating) {
state->floating->length = 0;
} else {
state->floating = create_list();
}
if (state->tiling) {
state->tiling->length = 0;
} else {
state->tiling = create_list();
}
list_cat(state->floating, ws->floating);
list_cat(state->tiling, ws->tiling);
@ -147,7 +159,11 @@ static void copy_container_state(struct sway_container *container,
state->content_height = container->content_height;
if (!container->view) {
state->children = create_list();
if (state->children) {
state->children->length = 0;
} else {
state->children = create_list();
}
list_cat(state->children, container->children);
}
@ -163,13 +179,32 @@ static void copy_container_state(struct sway_container *container,
static void transaction_add_node(struct sway_transaction *transaction,
struct sway_node *node) {
struct sway_transaction_instruction *instruction =
calloc(1, sizeof(struct sway_transaction_instruction));
if (!sway_assert(instruction, "Unable to allocate instruction")) {
return;
struct sway_transaction_instruction *instruction = NULL;
// Check if we have an instruction for this node already, in which case we
// update that instead of creating a new one.
if (node->ntxnrefs > 0) {
for (int idx = 0; idx < transaction->instructions->length; idx++) {
struct sway_transaction_instruction *other =
transaction->instructions->items[idx];
if (other->node == node) {
instruction = other;
break;
}
}
}
if (!instruction) {
instruction = calloc(1, sizeof(struct sway_transaction_instruction));
if (!sway_assert(instruction, "Unable to allocate instruction")) {
return;
}
instruction->transaction = transaction;
instruction->node = node;
list_add(transaction->instructions, instruction);
node->ntxnrefs++;
}
instruction->transaction = transaction;
instruction->node = node;
switch (node->type) {
case N_ROOT:
@ -184,9 +219,6 @@ static void transaction_add_node(struct sway_transaction *transaction,
copy_container_state(node->sway_container, instruction);
break;
}
list_add(transaction->instructions, instruction);
node->ntxnrefs++;
}
static void apply_output_state(struct sway_output *output,
@ -307,70 +339,25 @@ static void transaction_apply(struct sway_transaction *transaction) {
cursor_rebase_all();
}
static void transaction_commit(struct sway_transaction *transaction);
static void transaction_commit_pending(void);
// Return true if both transactions operate on the same nodes
static bool transaction_same_nodes(struct sway_transaction *a,
struct sway_transaction *b) {
if (a->instructions->length != b->instructions->length) {
return false;
}
for (int i = 0; i < a->instructions->length; ++i) {
struct sway_transaction_instruction *a_inst = a->instructions->items[i];
struct sway_transaction_instruction *b_inst = b->instructions->items[i];
if (a_inst->node != b_inst->node) {
return false;
}
}
return true;
}
static void transaction_progress_queue(void) {
if (!server.transactions->length) {
static void transaction_progress(void) {
if (!server.queued_transaction) {
return;
}
// Only the first transaction in the queue is committed, so that's the one
// we try to process.
struct sway_transaction *transaction = server.transactions->items[0];
if (transaction->num_waiting) {
if (server.queued_transaction->num_waiting > 0) {
return;
}
transaction_apply(transaction);
transaction_destroy(transaction);
list_del(server.transactions, 0);
transaction_apply(server.queued_transaction);
transaction_destroy(server.queued_transaction);
server.queued_transaction = NULL;
if (server.transactions->length == 0) {
// The transaction queue is empty, so we're done.
if (!server.pending_transaction) {
sway_idle_inhibit_v1_check_active(server.idle_inhibit_manager_v1);
return;
}
// If there's a bunch of consecutive transactions which all apply to the
// same views, skip all except the last one.
while (server.transactions->length >= 2) {
struct sway_transaction *txn = server.transactions->items[0];
struct sway_transaction *dup = NULL;
for (int i = 1; i < server.transactions->length; i++) {
struct sway_transaction *maybe_dup = server.transactions->items[i];
if (transaction_same_nodes(txn, maybe_dup)) {
dup = maybe_dup;
break;
}
}
if (dup) {
list_del(server.transactions, 0);
transaction_destroy(txn);
} else {
break;
}
}
// We again commit the first transaction in the queue to process it.
transaction = server.transactions->items[0];
transaction_commit(transaction);
transaction_progress_queue();
transaction_commit_pending();
}
static int handle_timeout(void *data) {
@ -378,7 +365,7 @@ static int handle_timeout(void *data) {
sway_log(SWAY_DEBUG, "Transaction %p timed out (%zi waiting)",
transaction, transaction->num_waiting);
transaction->num_waiting = 0;
transaction_progress_queue();
transaction_progress();
return 0;
}
@ -479,6 +466,17 @@ static void transaction_commit(struct sway_transaction *transaction) {
}
}
static void transaction_commit_pending(void) {
if (server.queued_transaction) {
return;
}
struct sway_transaction *transaction = server.pending_transaction;
server.pending_transaction = NULL;
server.queued_transaction = transaction;
transaction_commit(transaction);
transaction_progress();
}
static void set_instruction_ready(
struct sway_transaction_instruction *instruction) {
struct sway_transaction *transaction = instruction->transaction;
@ -504,7 +502,7 @@ static void set_instruction_ready(
}
instruction->node->instruction = NULL;
transaction_progress_queue();
transaction_progress();
}
void transaction_notify_view_ready_by_serial(struct sway_view *view,
@ -541,24 +539,20 @@ void transaction_commit_dirty(void) {
if (!server.dirty_nodes->length) {
return;
}
struct sway_transaction *transaction = transaction_create();
if (!transaction) {
return;
if (!server.pending_transaction) {
server.pending_transaction = transaction_create();
if (!server.pending_transaction) {
return;
}
}
for (int i = 0; i < server.dirty_nodes->length; ++i) {
struct sway_node *node = server.dirty_nodes->items[i];
transaction_add_node(transaction, node);
transaction_add_node(server.pending_transaction, node);
node->dirty = false;
}
server.dirty_nodes->length = 0;
list_add(server.transactions, transaction);
// We only commit the first transaction added to the queue.
if (server.transactions->length == 1) {
transaction_commit(transaction);
// Attempting to progress the queue here is useful
// if the transaction has nothing to wait for.
transaction_progress_queue();
}
transaction_commit_pending();
}

2
sway/server.c
View file

@ -199,7 +199,6 @@ bool server_init(struct sway_server *server) {
}
server->dirty_nodes = create_list();
server->transactions = create_list();
server->input = input_manager_create(server);
input_manager_get_default_seat(); // create seat0
@ -215,7 +214,6 @@ void server_fini(struct sway_server *server) {
wl_display_destroy_clients(server->wl_display);
wl_display_destroy(server->wl_display);
list_free(server->dirty_nodes);
list_free(server->transactions);
}
bool server_start(struct sway_server *server) {