--- /dev/null
+/*
+ * lttng-context-provider.c
+ *
+ * LTTng UST application context provider.
+ *
+ * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <sys/types.h>
+#include <unistd.h>
+#include <lttng/ust-context-provider.h>
+#include "lttng-tracer-core.h"
+#include "jhash.h"
+#include <helper.h>
+
+#define CONTEXT_PROVIDER_HT_BITS 12
+#define CONTEXT_PROVIDER_HT_SIZE (1U << CONTEXT_PROVIDER_HT_BITS)
+struct context_provider_ht {
+ struct cds_hlist_head table[CONTEXT_PROVIDER_HT_SIZE];
+};
+
+static struct context_provider_ht context_provider_ht;
+
+static struct lttng_ust_context_provider *
+ lookup_provider_by_name(const char *name)
+{
+ struct cds_hlist_head *head;
+ struct cds_hlist_node *node;
+ struct lttng_ust_context_provider *provider;
+ uint32_t hash;
+ const char *end;
+ size_t len;
+
+ /* Lookup using everything before first ':' as key. */
+ end = strchr(name, ':');
+ if (end)
+ len = end - name;
+ else
+ len = strlen(name);
+ hash = jhash(name, len, 0);
+ head = &context_provider_ht.table[hash & (CONTEXT_PROVIDER_HT_SIZE - 1)];
+ cds_hlist_for_each_entry(provider, node, head, node) {
+ if (!strncmp(provider->name, name, len))
+ return provider;
+ }
+ return NULL;
+}
+
+int lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider)
+{
+ struct cds_hlist_head *head;
+ size_t name_len = strlen(provider->name);
+ uint32_t hash;
+ int ret = 0;
+
+ /* Provider name starts with "$app.". */
+ if (strncmp("$app.", provider->name, strlen("$app.") != 0))
+ return -EINVAL;
+ /* Provider name cannot contain a column character. */
+ if (strchr(provider->name, ':'))
+ return -EINVAL;
+ if (ust_lock()) {
+ ret = -EBUSY;
+ goto end;
+ }
+ if (lookup_provider_by_name(provider->name)) {
+ ret = -EBUSY;
+ goto end;
+ }
+ hash = jhash(provider->name, name_len, 0);
+ head = &context_provider_ht.table[hash & (CONTEXT_PROVIDER_HT_SIZE - 1)];
+ cds_hlist_add_head(&provider->node, head);
+ lttng_ust_context_set_session_provider(provider->name,
+ provider->get_size, provider->record,
+ provider->get_value);
+end:
+ ust_unlock();
+ return ret;
+}
+
+static
+size_t dummy_get_size(struct lttng_ctx_field *field, size_t offset)
+{
+ size_t size = 0;
+
+ size += lib_ring_buffer_align(offset, lttng_alignof(char));
+ size += sizeof(char); /* tag */
+ return size;
+}
+
+static
+void dummy_record(struct lttng_ctx_field *field,
+ struct lttng_ust_lib_ring_buffer_ctx *ctx,
+ struct lttng_channel *chan)
+{
+ char sel_char = (char) LTTNG_UST_DYNAMIC_TYPE_NONE;
+
+ lib_ring_buffer_align_ctx(ctx, lttng_alignof(sel_char));
+ chan->ops->event_write(ctx, &sel_char, sizeof(sel_char));
+}
+
+static
+void dummy_get_value(struct lttng_ctx_field *field,
+ struct lttng_ctx_value *value)
+{
+ value->sel = LTTNG_UST_DYNAMIC_TYPE_NONE;
+}
+
+void lttng_ust_context_provider_unregister(struct lttng_ust_context_provider *provider)
+{
+ if (ust_lock())
+ goto end;
+ lttng_ust_context_set_session_provider(provider->name,
+ dummy_get_size, dummy_record, dummy_get_value);
+ cds_hlist_del(&provider->node);
+end:
+ ust_unlock();
+}
+
+/*
+ * Called with ust mutex held.
+ * Add application context to array of context, even if the application
+ * context is not currently loaded by application. It will then use the
+ * dummy callbacks in that case.
+ * Always performed before tracing is started, since it modifies
+ * metadata describing the context.
+ */
+int lttng_ust_add_app_context_to_ctx_rcu(const char *name,
+ struct lttng_ctx **ctx)
+{
+ struct lttng_ust_context_provider *provider;
+ struct lttng_ctx_field new_field;
+ int ret;
+
+ if (*ctx && lttng_find_context(*ctx, name))
+ return -EEXIST;
+ /*
+ * For application context, add it by expanding
+ * ctx array.
+ */
+ memset(&new_field, 0, sizeof(new_field));
+ new_field.field_name = strdup(name);
+ if (!new_field.field_name)
+ return -ENOMEM;
+ new_field.event_field.name = new_field.field_name;
+ new_field.event_field.type.atype = atype_dynamic;
+ /*
+ * If provider is not found, we add the context anyway, but
+ * it will provide a dummy context.
+ */
+ provider = lookup_provider_by_name(name);
+ if (provider) {
+ new_field.get_size = provider->get_size;
+ new_field.record = provider->record;
+ new_field.get_value = provider->get_value;
+ } else {
+ new_field.get_size = dummy_get_size;
+ new_field.record = dummy_record;
+ new_field.get_value = dummy_get_value;
+ }
+ ret = lttng_context_add_rcu(ctx, &new_field);
+ if (ret) {
+ free(new_field.field_name);
+ return ret;
+ }
+ return 0;
+}
projects / deliverable / lttng-ust.git / blobdiff