realm-js/shared_realm.cpp

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////////////////////////////////////////////////////////////////////////////
//
// Copyright 2015 Realm Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////
#include "shared_realm.hpp"
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#include "realm_delegate.hpp"
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#include <realm/commit_log.hpp>
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#include <realm/group_shared.hpp>
#include <realm/lang_bind_helper.hpp>
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#include <mutex>
#include <numeric>
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using namespace realm;
namespace {
class TransactLogHandler {
using ColumnInfo = RealmDelegate::ColumnInfo;
using ObserverState = RealmDelegate::ObserverState;
size_t currentTable = 0;
std::vector<ObserverState> observers;
std::vector<void *> invalidated;
ColumnInfo *activeLinkList = nullptr;
RealmDelegate* m_delegate;
// Get the change info for the given column, creating it if needed
static ColumnInfo& get_change(ObserverState& state, size_t i)
{
if (state.changes.size() <= i) {
state.changes.resize(std::max(state.changes.size() * 2, i + 1));
}
return state.changes[i];
}
// Loop over the columns which were changed in an observer state
template<typename Func>
static void for_each(ObserverState& state, Func&& f)
{
for (size_t i = 0; i < state.changes.size(); ++i) {
auto const& change = state.changes[i];
if (change.changed) {
f(i, change);
}
}
}
// Mark the given row/col as needing notifications sent
bool mark_dirty(size_t row_ndx, size_t col_ndx)
{
auto it = lower_bound(begin(observers), end(observers), ObserverState{currentTable, row_ndx, nullptr});
if (it != end(observers) && it->table_ndx == currentTable && it->row_ndx == row_ndx) {
get_change(*it, col_ndx).changed = true;
}
return true;
}
// Remove the given observer from the list of observed objects and add it
// to the listed of invalidated objects
void invalidate(ObserverState *o)
{
invalidated.push_back(o->info);
observers.erase(observers.begin() + (o - &observers[0]));
}
public:
template<typename Func>
TransactLogHandler(RealmDelegate* delegate, SharedGroup& sg, Func&& func)
: m_delegate(delegate)
{
if (!delegate) {
func();
return;
}
observers = delegate->get_observed_rows();
if (observers.empty()) {
auto old_version = sg.get_version_of_current_transaction();
func();
if (old_version != sg.get_version_of_current_transaction()) {
delegate->did_change({}, {});
}
return;
}
func(*this);
delegate->did_change(observers, invalidated);
}
// Called at the end of the transaction log immediately before the version
// is advanced
void parse_complete()
{
m_delegate->will_change(observers, invalidated);
}
// These would require having an observer before schema init
// Maybe do something here to throw an error when multiple processes have different schemas?
bool insert_group_level_table(size_t, size_t, StringData) noexcept { return false; }
bool erase_group_level_table(size_t, size_t) noexcept { return false; }
bool rename_group_level_table(size_t, StringData) noexcept { return false; }
bool insert_column(size_t, DataType, StringData, bool) { return false; }
bool insert_link_column(size_t, DataType, StringData, size_t, size_t) { return false; }
bool erase_column(size_t) { return false; }
bool erase_link_column(size_t, size_t, size_t) { return false; }
bool rename_column(size_t, StringData) { return false; }
bool add_search_index(size_t) { return false; }
bool remove_search_index(size_t) { return false; }
bool add_primary_key(size_t) { return false; }
bool remove_primary_key() { return false; }
bool set_link_type(size_t, LinkType) { return false; }
bool select_table(size_t group_level_ndx, int, const size_t*) noexcept {
currentTable = group_level_ndx;
return true;
}
bool insert_empty_rows(size_t, size_t, size_t, bool) {
// rows are only inserted at the end, so no need to do anything
return true;
}
bool erase_rows(size_t row_ndx, size_t, size_t last_row_ndx, bool unordered) noexcept {
for (size_t i = 0; i < observers.size(); ++i) {
auto& o = observers[i];
if (o.table_ndx == currentTable) {
if (o.row_ndx == row_ndx) {
invalidate(&o);
--i;
}
else if (unordered && o.row_ndx == last_row_ndx) {
o.row_ndx = row_ndx;
}
else if (!unordered && o.row_ndx > row_ndx) {
o.row_ndx -= 1;
}
}
}
return true;
}
bool clear_table() noexcept {
for (size_t i = 0; i < observers.size(); ) {
auto& o = observers[i];
if (o.table_ndx == currentTable) {
invalidate(&o);
}
else {
++i;
}
}
return true;
}
bool select_link_list(size_t col, size_t row) {
activeLinkList = nullptr;
for (auto& o : observers) {
if (o.table_ndx == currentTable && o.row_ndx == row) {
activeLinkList = &get_change(o, col);
break;
}
}
return true;
}
void append_link_list_change(ColumnInfo::Kind kind, size_t index) {
ColumnInfo *o = activeLinkList;
if (!o || o->kind == ColumnInfo::Kind::SetAll) {
// Active LinkList isn't observed or already has multiple kinds of changes
return;
}
if (o->kind == ColumnInfo::Kind::None) {
o->kind = kind;
o->changed = true;
o->indices.add(index);
}
else if (o->kind == kind) {
if (kind == ColumnInfo::Kind::Remove) {
// Shift the index to compensate for already-removed indices
for (auto i : o->indices) {
if (i <= index)
++index;
else
break;
}
o->indices.add(index);
}
else if (kind == ColumnInfo::Kind::Insert) {
o->indices.insert_at(index);
}
else {
o->indices.add(index);
}
}
else {
// Array KVO can only send a single kind of change at a time, so
// if there's multiple just give up and send "Set"
o->indices.set(0);
o->kind = ColumnInfo::Kind::SetAll;
}
}
bool link_list_set(size_t index, size_t) {
append_link_list_change(ColumnInfo::Kind::Set, index);
return true;
}
bool link_list_insert(size_t index, size_t) {
append_link_list_change(ColumnInfo::Kind::Insert, index);
return true;
}
bool link_list_erase(size_t index) {
append_link_list_change(ColumnInfo::Kind::Remove, index);
return true;
}
bool link_list_nullify(size_t index) {
append_link_list_change(ColumnInfo::Kind::Remove, index);
return true;
}
bool link_list_swap(size_t index1, size_t index2) {
append_link_list_change(ColumnInfo::Kind::Set, index1);
append_link_list_change(ColumnInfo::Kind::Set, index2);
return true;
}
bool link_list_clear(size_t old_size) {
ColumnInfo *o = activeLinkList;
if (!o || o->kind == ColumnInfo::Kind::SetAll) {
return true;
}
if (o->kind == ColumnInfo::Kind::Remove)
old_size += o->indices.size();
else if (o->kind == ColumnInfo::Kind::Insert)
old_size -= o->indices.size();
o->indices.set(old_size);
o->kind = ColumnInfo::Kind::Remove;
o->changed = true;
return true;
}
bool link_list_move(size_t from, size_t to) {
ColumnInfo *o = activeLinkList;
if (!o || o->kind == ColumnInfo::Kind::SetAll) {
return true;
}
if (from > to) {
std::swap(from, to);
}
if (o->kind == ColumnInfo::Kind::None) {
o->kind = ColumnInfo::Kind::Set;
o->changed = true;
}
if (o->kind == ColumnInfo::Kind::Set) {
for (size_t i = from; i <= to; ++i)
o->indices.add(i);
}
else {
o->indices.set(0);
o->kind = ColumnInfo::Kind::SetAll;
}
return true;
}
// Things that just mark the field as modified
bool set_int(size_t col, size_t row, int_fast64_t) { return mark_dirty(row, col); }
bool set_bool(size_t col, size_t row, bool) { return mark_dirty(row, col); }
bool set_float(size_t col, size_t row, float) { return mark_dirty(row, col); }
bool set_double(size_t col, size_t row, double) { return mark_dirty(row, col); }
bool set_string(size_t col, size_t row, StringData) { return mark_dirty(row, col); }
bool set_binary(size_t col, size_t row, BinaryData) { return mark_dirty(row, col); }
bool set_date_time(size_t col, size_t row, DateTime) { return mark_dirty(row, col); }
bool set_table(size_t col, size_t row) { return mark_dirty(row, col); }
bool set_mixed(size_t col, size_t row, const Mixed&) { return mark_dirty(row, col); }
bool set_link(size_t col, size_t row, size_t) { return mark_dirty(row, col); }
bool set_null(size_t col, size_t row) { return mark_dirty(row, col); }
bool nullify_link(size_t col, size_t row) { return mark_dirty(row, col); }
// Things we don't need to do anything for
bool optimize_table() { return false; }
// Things that we don't do in the binding
bool select_descriptor(int, const size_t*) { return true; }
bool add_int_to_column(size_t, int_fast64_t) { return false; }
};
}
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RealmCache Realm::s_global_cache;
Realm::Config::Config(const Config& c)
: path(c.path)
, read_only(c.read_only)
, in_memory(c.in_memory)
, cache(c.cache)
, encryption_key(c.encryption_key)
, schema_version(c.schema_version)
, migration_function(c.migration_function)
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{
if (c.schema) {
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schema = std::make_unique<Schema>(*c.schema);
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}
}
Realm::Config& Realm::Config::operator=(realm::Realm::Config const& c)
{
if (&c != this) {
*this = Config(c);
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}
return *this;
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}
Realm::Realm(Config config) : m_config(std::move(config))
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{
try {
if (m_config.read_only) {
m_read_only_group = std::make_unique<Group>(m_config.path, m_config.encryption_key.data(), Group::mode_ReadOnly);
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m_group = m_read_only_group.get();
}
else {
m_history = realm::make_client_history(m_config.path, m_config.encryption_key.data());
SharedGroup::DurabilityLevel durability = m_config.in_memory ? SharedGroup::durability_MemOnly :
SharedGroup::durability_Full;
m_shared_group = std::make_unique<SharedGroup>(*m_history, durability, m_config.encryption_key.data());
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}
}
catch (util::File::PermissionDenied const& ex) {
throw RealmFileException(RealmFileException::Kind::PermissionDenied, "Unable to open a realm at path '" + m_config.path +
"'. Please use a path where your app has " + (m_config.read_only ? "read" : "read-write") + " permissions.");
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}
catch (util::File::Exists const& ex) {
throw RealmFileException(RealmFileException::Kind::Exists, "Unable to open a realm at path '" + m_config.path + "'");
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}
catch (util::File::AccessError const& ex) {
throw RealmFileException(RealmFileException::Kind::AccessError, "Unable to open a realm at path '" + m_config.path + "'");
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}
catch (IncompatibleLockFile const&) {
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throw RealmFileException(RealmFileException::Kind::IncompatibleLockFile, "Realm file is currently open in another process "
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"which cannot share access with this process. All processes sharing a single file must be the same architecture.");
}
}
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Group *Realm::read_group()
{
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if (!m_group) {
m_group = &const_cast<Group&>(m_shared_group->begin_read());
}
return m_group;
}
SharedRealm Realm::get_shared_realm(Config config)
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{
if (config.cache) {
if (SharedRealm realm = s_global_cache.get_realm(config.path)) {
if (realm->config().read_only != config.read_only) {
throw MismatchedConfigException("Realm at path already opened with different read permissions.");
}
if (realm->config().in_memory != config.in_memory) {
throw MismatchedConfigException("Realm at path already opened with different inMemory settings.");
}
if (realm->config().encryption_key != config.encryption_key) {
throw MismatchedConfigException("Realm at path already opened with a different encryption key.");
}
if (realm->config().schema_version != config.schema_version && config.schema_version != ObjectStore::NotVersioned) {
throw MismatchedConfigException("Realm at path already opened with different schema version.");
}
// FIXME - enable schma comparison
/*if (realm->config().schema != config.schema) {
throw MismatchedConfigException("Realm at path already opened with different schema");
}*/
realm->m_config.migration_function = config.migration_function;
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return realm;
}
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}
SharedRealm realm(new Realm(std::move(config)));
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// we want to ensure we are only initializing a single realm at a time
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static std::mutex s_init_mutex;
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std::lock_guard<std::mutex> lock(s_init_mutex);
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uint64_t old_version = ObjectStore::get_schema_version(realm->read_group());
if (auto existing = s_global_cache.get_any_realm(realm->config().path)) {
// if there is an existing realm at the current path steal its schema/column mapping
// FIXME - need to validate that schemas match
realm->m_config.schema = std::make_unique<Schema>(*existing->m_config.schema);
}
else if (!realm->m_config.schema) {
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// get schema from group and skip validation
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realm->m_config.schema_version = old_version;
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realm->m_config.schema = std::make_unique<Schema>(ObjectStore::schema_from_group(realm->read_group()));
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}
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else if (realm->m_config.read_only) {
if (old_version == ObjectStore::NotVersioned) {
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throw UnitializedRealmException("Can't open an un-initialized Realm without a Schema");
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}
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ObjectStore::verify_schema(realm->read_group(), *realm->m_config.schema, true);
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}
else {
// its a non-cached realm so update/migrate if needed
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realm->update_schema(*realm->m_config.schema, realm->m_config.schema_version);
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}
if (config.cache) {
s_global_cache.cache_realm(realm, realm->m_thread_id);
}
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return realm;
}
bool Realm::update_schema(Schema const& schema, uint64_t version)
{
bool changed = false;
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Config old_config(m_config);
// set new version/schema
if (m_config.schema.get() != &schema) {
m_config.schema = std::make_unique<Schema>(schema);
}
m_config.schema_version = version;
try {
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if (!m_config.read_only && ObjectStore::realm_requires_update(read_group(), version, schema)) {
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// keep old copy to pass to migration function
old_config.read_only = true;
old_config.schema_version = ObjectStore::get_schema_version(read_group());
old_config.schema = std::make_unique<Schema>(ObjectStore::schema_from_group(read_group()));
SharedRealm old_realm(new Realm(old_config));
auto updated_realm = shared_from_this();
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// update and migrate
begin_transaction();
changed = ObjectStore::update_realm_with_schema(read_group(), version, *m_config.schema,
[=](__unused Group *group, __unused Schema &target_schema) {
m_config.migration_function(old_realm, updated_realm);
});
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commit_transaction();
}
else {
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ObjectStore::verify_schema(read_group(), *m_config.schema, m_config.read_only);
}
}
catch (...) {
if (is_in_transaction()) {
cancel_transaction();
}
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m_config.schema_version = old_config.schema_version;
m_config.schema = std::move(old_config.schema);
throw;
}
return changed;
}
static void check_read_write(Realm *realm)
{
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if (realm->config().read_only) {
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throw InvalidTransactionException("Can't perform transactions on read-only Realms.");
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}
}
void Realm::verify_thread()
{
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if (m_thread_id != std::this_thread::get_id()) {
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throw IncorrectThreadException("Realm accessed from incorrect thread.");
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}
}
void Realm::begin_transaction()
{
check_read_write(this);
verify_thread();
if (m_in_transaction) {
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throw InvalidTransactionException("The Realm is already in a write transaction");
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}
// make sure we have a read transaction
read_group();
TransactLogHandler(m_delegate.get(), *m_shared_group, [&](auto&&... args) {
LangBindHelper::promote_to_write(*m_shared_group, *m_history, std::move(args)...);
});
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m_in_transaction = true;
}
void Realm::commit_transaction()
{
check_read_write(this);
verify_thread();
if (!m_in_transaction) {
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throw InvalidTransactionException("Can't commit a non-existing write transaction");
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}
LangBindHelper::commit_and_continue_as_read(*m_shared_group);
m_in_transaction = false;
if (m_delegate) {
m_delegate->transaction_committed();
}
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}
void Realm::cancel_transaction()
{
check_read_write(this);
verify_thread();
if (!m_in_transaction) {
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throw InvalidTransactionException("Can't cancel a non-existing write transaction");
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}
TransactLogHandler(m_delegate.get(), *m_shared_group, [&](auto&&... args) {
LangBindHelper::rollback_and_continue_as_read(*m_shared_group, *m_history, std::move(args)...);
});
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m_in_transaction = false;
}
void Realm::invalidate()
{
verify_thread();
check_read_write(this);
if (m_in_transaction) {
cancel_transaction();
}
if (!m_group) {
return;
}
m_shared_group->end_read();
m_group = nullptr;
}
bool Realm::compact()
{
verify_thread();
bool success = false;
if (m_in_transaction) {
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throw InvalidTransactionException("Can't compact a Realm within a write transaction");
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}
for (auto &object_schema : *m_config.schema) {
ObjectStore::table_for_object_type(read_group(), object_schema.name)->optimize();
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}
m_shared_group->end_read();
success = m_shared_group->compact();
m_shared_group->begin_read();
return success;
}
void Realm::notify()
{
verify_thread();
if (m_shared_group->has_changed()) { // Throws
if (m_auto_refresh) {
if (m_group) {
TransactLogHandler(m_delegate.get(), *m_shared_group, [&](auto&&... args) {
LangBindHelper::advance_read(*m_shared_group, *m_history, std::move(args)...);
});
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}
else if (m_delegate) {
m_delegate->did_change({}, {});
}
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}
else if (m_delegate) {
m_delegate->changes_available();
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}
}
}
bool Realm::refresh()
{
verify_thread();
check_read_write(this);
// can't be any new changes if we're in a write transaction
if (m_in_transaction) {
return false;
}
// advance transaction if database has changed
if (!m_shared_group->has_changed()) { // Throws
return false;
}
if (m_group) {
TransactLogHandler(m_delegate.get(), *m_shared_group, [&](auto&&... args) {
LangBindHelper::advance_read(*m_shared_group, *m_history, std::move(args)...);
});
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}
else {
// Create the read transaction
read_group();
}
return true;
}
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uint64_t Realm::get_schema_version(const realm::Realm::Config &config)
{
auto existing_realm = s_global_cache.get_any_realm(config.path);
if (existing_realm) {
return existing_realm->config().schema_version;
}
return ObjectStore::get_schema_version(Realm(config).read_group());
}
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SharedRealm RealmCache::get_realm(const std::string &path, std::thread::id thread_id)
{
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std::lock_guard<std::mutex> lock(m_mutex);
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auto path_iter = m_cache.find(path);
if (path_iter == m_cache.end()) {
return SharedRealm();
}
auto thread_iter = path_iter->second.find(thread_id);
if (thread_iter == path_iter->second.end()) {
return SharedRealm();
}
return thread_iter->second.lock();
}
SharedRealm RealmCache::get_any_realm(const std::string &path)
{
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std::lock_guard<std::mutex> lock(m_mutex);
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auto path_iter = m_cache.find(path);
if (path_iter == m_cache.end()) {
return SharedRealm();
}
auto thread_iter = path_iter->second.begin();
while (thread_iter != path_iter->second.end()) {
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if (auto realm = thread_iter->second.lock()) {
return realm;
}
path_iter->second.erase(thread_iter++);
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}
return SharedRealm();
}
void RealmCache::remove(const std::string &path, std::thread::id thread_id)
{
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std::lock_guard<std::mutex> lock(m_mutex);
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auto path_iter = m_cache.find(path);
if (path_iter == m_cache.end()) {
return;
}
auto thread_iter = path_iter->second.find(thread_id);
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if (thread_iter != path_iter->second.end()) {
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path_iter->second.erase(thread_iter);
}
if (path_iter->second.size() == 0) {
m_cache.erase(path_iter);
}
}
void RealmCache::cache_realm(SharedRealm &realm, std::thread::id thread_id)
{
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std::lock_guard<std::mutex> lock(m_mutex);
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auto path_iter = m_cache.find(realm->config().path);
if (path_iter == m_cache.end()) {
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m_cache.emplace(realm->config().path, std::map<std::thread::id, WeakRealm>{{thread_id, realm}});
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}
else {
path_iter->second.emplace(thread_id, realm);
}
}
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void RealmCache::clear()
{
std::lock_guard<std::mutex> lock(m_mutex);
m_cache.clear();
}