hw/xen: Watches on XenStore transactions
Firing watches on the nodes that still exist is relatively easy; just walk the tree and look at the nodes with refcount of one. Firing watches on *deleted* nodes is more fun. We add 'modified_in_tx' and 'deleted_in_tx' flags to each node. Nodes with those flags cannot be shared, as they will always be unique to the transaction in which they were created. When xs_node_walk would need to *create* a node as scaffolding and it encounters a deleted_in_tx node, it can resurrect it simply by clearing its deleted_in_tx flag. If that node originally had any *data*, they're gone, and the modified_in_tx flag will have been set when it was first deleted. We then attempt to send appropriate watches when the transaction is committed, properly delete the deleted_in_tx nodes, and remove the modified_in_tx flag from the others. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Paul Durrant <paul@xen.org>
This commit is contained in:
David Woodhouse
parent
7248b87cb0
commit
7cabbdb70d
2 changed files with 380 additions and 2 deletions
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@ -347,7 +347,13 @@ static void do_test_xs_node_tx(bool fail, bool commit)
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} else {
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g_assert(!err);
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}
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g_assert(!watches->len);
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if (commit && !fail) {
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g_assert(!strcmp(watches->str,
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"some/relative/pathwatch"));
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g_string_truncate(watches, 0);
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} else {
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g_assert(!watches->len);
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}
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g_assert(s->nr_nodes == 7);
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err = xs_impl_unwatch(s, DOMID_GUEST, "some", "watch",
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@ -386,6 +392,226 @@ static void test_xs_node_tx_succeed(void)
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do_test_xs_node_tx(false, true);
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}
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static void test_xs_node_tx_rm(void)
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{
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XenstoreImplState *s = setup();
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GString *watches = g_string_new(NULL);
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GByteArray *data = g_byte_array_new();
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unsigned int tx_id = XBT_NULL;
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int err;
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g_assert(s);
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/* Set a watch */
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err = xs_impl_watch(s, DOMID_GUEST, "some", "watch",
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watch_cb, watches);
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g_assert(!err);
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g_assert(watches->len == strlen("somewatch"));
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g_assert(!strcmp(watches->str, "somewatch"));
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g_string_truncate(watches, 0);
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/* Write something */
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err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
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"something");
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g_assert(!err);
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g_assert(s->nr_nodes == 9);
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g_assert(!strcmp(watches->str,
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"some/deep/dark/relative/pathwatch"));
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g_string_truncate(watches, 0);
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/* Create a transaction */
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err = xs_impl_transaction_start(s, DOMID_GUEST, &tx_id);
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g_assert(!err);
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/* Delete the tree in the transaction */
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err = xs_impl_rm(s, DOMID_GUEST, tx_id, "some/deep/dark");
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g_assert(!err);
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g_assert(s->nr_nodes == 9);
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g_assert(!watches->len);
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err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
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data);
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g_assert(!err);
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g_assert(data->len == strlen("something"));
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g_assert(!memcmp(data->data, "something", data->len));
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g_byte_array_set_size(data, 0);
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/* Commit the transaction */
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err = xs_impl_transaction_end(s, DOMID_GUEST, tx_id, true);
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g_assert(!err);
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g_assert(s->nr_nodes == 6);
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g_assert(!strcmp(watches->str, "some/deep/darkwatch"));
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g_string_truncate(watches, 0);
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/* Now the node is gone */
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err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
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data);
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g_assert(err == ENOENT);
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g_byte_array_unref(data);
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err = xs_impl_unwatch(s, DOMID_GUEST, "some", "watch",
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watch_cb, watches);
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g_assert(!err);
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g_string_free(watches, true);
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xs_impl_delete(s);
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}
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static void test_xs_node_tx_resurrect(void)
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{
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XenstoreImplState *s = setup();
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GString *watches = g_string_new(NULL);
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GByteArray *data = g_byte_array_new();
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unsigned int tx_id = XBT_NULL;
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int err;
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g_assert(s);
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/* Write something */
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err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
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"something");
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g_assert(!err);
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g_assert(s->nr_nodes == 9);
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/* This node will be wiped and resurrected */
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err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark",
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"foo");
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g_assert(!err);
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g_assert(s->nr_nodes == 9);
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/* Set a watch */
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err = xs_impl_watch(s, DOMID_GUEST, "some", "watch",
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watch_cb, watches);
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g_assert(!err);
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g_assert(watches->len == strlen("somewatch"));
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g_assert(!strcmp(watches->str, "somewatch"));
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g_string_truncate(watches, 0);
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/* Create a transaction */
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err = xs_impl_transaction_start(s, DOMID_GUEST, &tx_id);
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g_assert(!err);
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/* Delete the tree in the transaction */
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err = xs_impl_rm(s, DOMID_GUEST, tx_id, "some/deep");
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g_assert(!err);
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g_assert(s->nr_nodes == 9);
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g_assert(!watches->len);
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/* Resurrect part of it */
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err = write_str(s, DOMID_GUEST, tx_id, "some/deep/dark/different/path",
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"something");
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g_assert(!err);
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g_assert(s->nr_nodes == 9);
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/* Commit the transaction */
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err = xs_impl_transaction_end(s, DOMID_GUEST, tx_id, true);
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g_assert(!err);
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g_assert(s->nr_nodes == 9);
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/* lost data */
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g_assert(strstr(watches->str, "some/deep/dark/different/pathwatch"));
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/* topmost deleted */
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g_assert(strstr(watches->str, "some/deep/dark/relativewatch"));
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/* lost data */
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g_assert(strstr(watches->str, "some/deep/darkwatch"));
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g_string_truncate(watches, 0);
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/* Now the node is gone */
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err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
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data);
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g_assert(err == ENOENT);
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g_byte_array_unref(data);
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err = xs_impl_unwatch(s, DOMID_GUEST, "some", "watch",
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watch_cb, watches);
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g_assert(!err);
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g_string_free(watches, true);
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xs_impl_delete(s);
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}
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static void test_xs_node_tx_resurrect2(void)
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{
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XenstoreImplState *s = setup();
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GString *watches = g_string_new(NULL);
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GByteArray *data = g_byte_array_new();
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unsigned int tx_id = XBT_NULL;
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int err;
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g_assert(s);
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/* Write something */
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err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
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"something");
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g_assert(!err);
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g_assert(s->nr_nodes == 9);
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/* Another node to remain shared */
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err = write_str(s, DOMID_GUEST, XBT_NULL, "some/place/safe", "keepme");
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g_assert(!err);
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g_assert(s->nr_nodes == 11);
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/* This node will be wiped and resurrected */
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err = write_str(s, DOMID_GUEST, XBT_NULL, "some/deep/dark",
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"foo");
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g_assert(!err);
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g_assert(s->nr_nodes == 11);
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/* Set a watch */
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err = xs_impl_watch(s, DOMID_GUEST, "some", "watch",
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watch_cb, watches);
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g_assert(!err);
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g_assert(watches->len == strlen("somewatch"));
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g_assert(!strcmp(watches->str, "somewatch"));
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g_string_truncate(watches, 0);
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/* Create a transaction */
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err = xs_impl_transaction_start(s, DOMID_GUEST, &tx_id);
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g_assert(!err);
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/* Delete the tree in the transaction */
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err = xs_impl_rm(s, DOMID_GUEST, tx_id, "some/deep");
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g_assert(!err);
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g_assert(s->nr_nodes == 11);
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g_assert(!watches->len);
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/* Resurrect part of it */
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err = write_str(s, DOMID_GUEST, tx_id, "some/deep/dark/relative/path",
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"something");
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g_assert(!err);
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g_assert(s->nr_nodes == 11);
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/* Commit the transaction */
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err = xs_impl_transaction_end(s, DOMID_GUEST, tx_id, true);
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g_assert(!err);
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g_assert(s->nr_nodes == 11);
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/* lost data */
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g_assert(strstr(watches->str, "some/deep/dark/relative/pathwatch"));
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/* lost data */
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g_assert(strstr(watches->str, "some/deep/darkwatch"));
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g_string_truncate(watches, 0);
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/* Now the node is gone */
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err = xs_impl_read(s, DOMID_GUEST, XBT_NULL, "some/deep/dark/relative/path",
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data);
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g_assert(!err);
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g_assert(data->len == strlen("something"));
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g_assert(!memcmp(data->data, "something", data->len));
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g_byte_array_unref(data);
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err = xs_impl_unwatch(s, DOMID_GUEST, "some", "watch",
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watch_cb, watches);
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g_assert(!err);
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g_string_free(watches, true);
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xs_impl_delete(s);
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}
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int main(int argc, char **argv)
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{
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g_test_init(&argc, &argv, NULL);
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@ -395,6 +621,9 @@ int main(int argc, char **argv)
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g_test_add_func("/xs_node/tx_abort", test_xs_node_tx_abort);
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g_test_add_func("/xs_node/tx_fail", test_xs_node_tx_fail);
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g_test_add_func("/xs_node/tx_succeed", test_xs_node_tx_succeed);
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g_test_add_func("/xs_node/tx_rm", test_xs_node_tx_rm);
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g_test_add_func("/xs_node/tx_resurrect", test_xs_node_tx_resurrect);
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g_test_add_func("/xs_node/tx_resurrect2", test_xs_node_tx_resurrect2);
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return g_test_run();
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}
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