Port some of the KVO support functionality to the object store

index_set.cpp

@@ -0,0 +1,117 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// 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 "index_set.hpp"
+
+using namespace realm;
+
+size_t IndexSet::size() const
+{
+    size_t size = 0;
+    for (auto const& range : m_ranges) {
+        size += range.second - range.first;
+    }
+    return size;
+}
+
+std::vector<IndexSet::Range>::iterator IndexSet::find(size_t index)
+{
+    for (auto it = m_ranges.begin(), end = m_ranges.end(); it != end; ++it) {
+        if (it->second > index)
+            return it;
+    }
+    return m_ranges.end();
+}
+
+void IndexSet::add(size_t index)
+{
+    do_add(find(index), index);
+}
+
+void IndexSet::do_add(std::vector<Range>::iterator it, size_t index)
+{
+    bool more_before = it != m_ranges.begin(), valid = it != m_ranges.end();
+    if (valid && it->first <= index && it->second > index) {
+        // index is already in set
+    }
+    else if (more_before && (it - 1)->second == index) {
+        // index is immediate after an existing range
+        ++(it - 1)->second;
+    }
+    else if (more_before && valid && (it - 1)->second == it->first) {
+        // index joins two existing ranges
+        (it - 1)->second = it->second;
+        m_ranges.erase(it);
+    }
+    else if (valid && it->first == index + 1) {
+        // index is immediately before an existing range
+        --it->first;
+    }
+    else {
+        // index is not next to an existing range
+        m_ranges.insert(it, {index, index + 1});
+    }
+}
+
+void IndexSet::set(size_t len)
+{
+    m_ranges.clear();
+    if (len) {
+        m_ranges.push_back({0, len});
+    }
+}
+
+void IndexSet::insert_at(size_t index)
+{
+    auto pos = find(index);
+    if (pos != m_ranges.end()) {
+        if (pos->first >= index)
+            ++pos->first;
+        ++pos->second;
+        for (auto it = pos + 1; it != m_ranges.end(); ++it) {
+            ++it->first;
+            ++it->second;
+        }
+    }
+    do_add(pos, index);
+}
+
+size_t IndexSet::iterator::operator*() const
+{
+    return m_data->first + m_offset;
+}
+
+IndexSet::iterator& IndexSet::iterator::operator++()
+{
+    ++m_offset;
+    if (m_offset + m_data->first == m_data->second) {
+        ++m_data;
+        m_offset = 0;
+    }
+    return *this;
+}
+
+bool IndexSet::iterator::operator==(iterator other) const
+{
+    return m_data == other.m_data && m_offset == other.m_offset;
+}
+
+bool IndexSet::iterator::operator!=(iterator other) const
+{
+    return m_data != other.m_data || m_offset != other.m_offset;
+}

index_set.hpp

@@ -0,0 +1,63 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// 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.
+//
+////////////////////////////////////////////////////////////////////////////
+
+#ifndef REALM_INDEX_SET_HPP
+#define REALM_INDEX_SET_HPP
+
+#include <vector>
+
+namespace realm {
+class IndexSet {
+public:
+    struct iterator {
+        size_t operator*() const;
+        iterator& operator++();
+        bool operator==(iterator) const;
+        bool operator!=(iterator) const;
+
+        iterator(std::pair<size_t, size_t>* data) noexcept : m_data(data) { }
+
+    private:
+        std::pair<size_t, size_t>* m_data;
+        size_t m_offset = 0;
+    };
+
+    iterator begin() { return iterator(&m_ranges[0]); }
+    iterator end() { return iterator(&m_ranges[m_ranges.size()]); }
+
+    size_t size() const;
+
+    // Add an index to the set, doing nothing if it's already present
+    void add(size_t index);
+    // Set the index set to a single range starting at 0 with length `len`
+    void set(size_t len);
+    // Insert an index at the given position, shifting existing indexes back
+    void insert_at(size_t index);
+
+private:
+    using Range = std::pair<size_t, size_t>;
+    std::vector<Range> m_ranges;
+
+    // Find the range which contains the index, or the first one after it if
+    // none do
+    std::vector<Range>::iterator find(size_t index);
+    void do_add(std::vector<Range>::iterator pos, size_t index);
+};
+} // namespace realm
+
+#endif // REALM_INDEX_SET_HPP

realm_delegate.hpp

@@ -0,0 +1,78 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// 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.
+//
+////////////////////////////////////////////////////////////////////////////
+
+#ifndef REALM_DELEGATE_HPP
+#define REALM_DELEGATE_HPP
+
+#include "index_set.hpp"
+
+#include <tuple>
+#include <vector>
+
+namespace realm {
+class RealmDelegate {
+public:
+    virtual ~RealmDelegate() = default;
+
+    struct ColumnInfo {
+        bool changed = false;
+        enum class Kind {
+            None,
+            Set,
+            Insert,
+            Remove,
+            SetAll
+        } kind = Kind::None;
+        IndexSet indices;
+    };
+
+    struct ObserverState {
+        size_t table_ndx;
+        size_t row_ndx;
+        void* info; // opaque user info
+        std::vector<ColumnInfo> changes;
+
+        // Simple lexographic ordering
+        friend bool operator<(ObserverState const& lft, ObserverState const& rgt) {
+            return std::tie(lft.table_ndx, lft.row_ndx) < std::tie(rgt.table_ndx, rgt.row_ndx);
+        }
+    };
+
+    // The Realm has committed a write transaction, and other Realms at the
+    // same path should be notified
+    virtual void transaction_committed() = 0;
+
+    // There are now new versions available for the Realm, but it has not
+    // had its read version advanced
+    virtual void changes_available() = 0;
+
+    // Called before changing the read transaction. Should return a list of
+    // ObserverStates for each row for which detailed change information is
+    // desired.
+    virtual std::vector<ObserverState> get_observed_rows() = 0;
+
+    // The Realm's read version will change
+    // Only called if get_observed_row() returned a non-empty array.
+    virtual void will_change(std::vector<ObserverState> const&, std::vector<void*> const&) = 0;
+
+    // The Realm's read version has changed
+    virtual void did_change(std::vector<ObserverState> const&, std::vector<void*> const&) = 0;
+};
+} // namespace realm
+
+#endif /* REALM_DELEGATE_HPP */

src/object-store/shared_realm.cpp

@@ -18,14 +18,296 @@
 
 #include "shared_realm.hpp"
 
+#include "realm_delegate.hpp"
+
 #include <realm/commit_log.hpp>
 #include <realm/group_shared.hpp>
 #include <realm/lang_bind_helper.hpp>
 
 #include <mutex>
+#include <numeric>
 
 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; }
+};
+}
+
 RealmCache Realm::s_global_cache;
 
 Realm::Config::Config(const Config& c)
@@ -214,18 +496,13 @@ void Realm::begin_transaction()
         throw InvalidTransactionException("The Realm is already in a write transaction");
     }
 
-    // if the upgrade to write will move the transaction forward, announce the change after promoting
-    bool announce = m_shared_group->has_changed();
-
     // make sure we have a read transaction
     read_group();
 
-    LangBindHelper::promote_to_write(*m_shared_group, *m_history);
+    TransactLogHandler(m_delegate.get(), *m_shared_group, [&](auto&&... args) {
+        LangBindHelper::promote_to_write(*m_shared_group, *m_history, std::move(args)...);
+    });
     m_in_transaction = true;
-
-    if (announce && m_delegate) {
-        m_delegate->did_change();
-    }
 }
 
 void Realm::commit_transaction()
@@ -242,7 +519,6 @@ void Realm::commit_transaction()
 
     if (m_delegate) {
         m_delegate->transaction_committed();
-        m_delegate->did_change();
     }
 }
 
@@ -255,7 +531,9 @@ void Realm::cancel_transaction()
         throw InvalidTransactionException("Can't cancel a non-existing write transaction");
     }
 
-    LangBindHelper::rollback_and_continue_as_read(*m_shared_group, *m_history);
+    TransactLogHandler(m_delegate.get(), *m_shared_group, [&](auto&&... args) {
+        LangBindHelper::rollback_and_continue_as_read(*m_shared_group, *m_history, std::move(args)...);
+    });
     m_in_transaction = false;
 }
 
@@ -303,10 +581,12 @@ void Realm::notify()
     if (m_shared_group->has_changed()) { // Throws
         if (m_auto_refresh) {
             if (m_group) {
-                LangBindHelper::advance_read(*m_shared_group, *m_history);
+                TransactLogHandler(m_delegate.get(), *m_shared_group, [&](auto&&... args) {
+                    LangBindHelper::advance_read(*m_shared_group, *m_history, std::move(args)...);
+                });
             }
-            if (m_delegate) {
-                m_delegate->did_change();
+            else if (m_delegate) {
+                m_delegate->did_change({}, {});
             }
         }
         else if (m_delegate) {
@@ -332,16 +612,15 @@ bool Realm::refresh()
     }
 
     if (m_group) {
-        LangBindHelper::advance_read(*m_shared_group, *m_history);
+        TransactLogHandler(m_delegate.get(), *m_shared_group, [&](auto&&... args) {
+            LangBindHelper::advance_read(*m_shared_group, *m_history, std::move(args)...);
+        });
     }
     else {
         // Create the read transaction
         read_group();
     }
 
-    if (m_delegate) {
-        m_delegate->did_change();
-    }
     return true;
 }
 

src/object-store/shared_realm.hpp

@@ -132,23 +132,6 @@ namespace realm {
         std::mutex m_mutex;
     };
 
-    class RealmDelegate
-    {
-    public:
-        virtual ~RealmDelegate() = default;
-
-        // The Realm has committed a write transaction, and other Realms at the
-        // same path should be notified
-        virtual void transaction_committed() = 0;
-
-        // There are now new versions available for the Realm, but it has not
-        // had its read version advanced
-        virtual void changes_available() = 0;
-
-        // The Realm's read version has advanced
-        virtual void did_change() = 0;
-    };
-
     class RealmFileException : public std::runtime_error
     {
       public: