From 50f737b8549fb1b380c753d36be3fafe0ec4a768 Mon Sep 17 00:00:00 2001
From: Christian Mollekopf <chrigi_1@fastmail.fm>
Date: Fri, 11 Sep 2015 09:31:24 +0200
Subject: Storage: substring search and findLatest

---
 common/storage.h          | 11 +++++++++--
 common/storage_common.cpp | 11 +++++++++++
 common/storage_lmdb.cpp   | 47 ++++++++++++++++++++++++++++++++++++++---------
 3 files changed, 58 insertions(+), 11 deletions(-)

(limited to 'common')

diff --git a/common/storage.h b/common/storage.h
index d186b2e..98b12ed 100644
--- a/common/storage.h
+++ b/common/storage.h
@@ -76,9 +76,13 @@ public:
         *
         * @return The number of values retrieved.
         */
-        int scan(const QByteArray &k,
+        int scan(const QByteArray &key,
                     const std::function<bool(const QByteArray &key, const QByteArray &value)> &resultHandler,
-                    const std::function<void(const Storage::Error &error)> &errorHandler = std::function<void(const Storage::Error &error)>()) const;
+                    const std::function<void(const Storage::Error &error)> &errorHandler = std::function<void(const Storage::Error &error)>(), bool findSubstringKeys = false) const;
+
+        void findLatest(const QByteArray &uid,
+                        const std::function<void(const QByteArray &key, const QByteArray &value)> &resultHandler,
+                        const std::function<void(const Storage::Error &error)> &errorHandler = std::function<void(const Storage::Error &error)>()) const;
 
         NamedDatabase(NamedDatabase&& other) : d(other.d)
         {
@@ -170,6 +174,9 @@ public:
     static bool isInternalKey(void *key, int keySize);
     static bool isInternalKey(const QByteArray &key);
 
+    static QByteArray assembleKey(const QByteArray &key, qint64 revision);
+    static QByteArray uidFromKey(const QByteArray &key);
+
 private:
     std::function<void(const Storage::Error &error)> mErrorHandler;
 
diff --git a/common/storage_common.cpp b/common/storage_common.cpp
index f22150a..28fb4c2 100644
--- a/common/storage_common.cpp
+++ b/common/storage_common.cpp
@@ -93,4 +93,15 @@ bool Storage::isInternalKey(const QByteArray &key)
     return key.startsWith(s_internalPrefix);
 }
 
+QByteArray Storage::assembleKey(const QByteArray &key, qint64 revision)
+{
+    Q_ASSERT(key.size() == 38);
+    return key + QByteArray::number(revision);
+}
+
+QByteArray Storage::uidFromKey(const QByteArray &key)
+{
+    return key.mid(0, 38);
+}
+
 } // namespace Akonadi2
diff --git a/common/storage_lmdb.cpp b/common/storage_lmdb.cpp
index a048a71..3073d37 100644
--- a/common/storage_lmdb.cpp
+++ b/common/storage_lmdb.cpp
@@ -169,7 +169,8 @@ void Storage::NamedDatabase::remove(const QByteArray &k,
 
 int Storage::NamedDatabase::scan(const QByteArray &k,
                   const std::function<bool(const QByteArray &key, const QByteArray &value)> &resultHandler,
-                  const std::function<void(const Storage::Error &error)> &errorHandler) const
+                  const std::function<void(const Storage::Error &error)> &errorHandler,
+                  bool findSubstringKeys) const
 {
     if (!d || !d->transaction) {
         //Not an error. We rely on this to read nothing from non-existing databases.
@@ -193,14 +194,25 @@ int Storage::NamedDatabase::scan(const QByteArray &k,
 
     int numberOfRetrievedValues = 0;
 
-    if (k.isEmpty() || d->allowDuplicates) {
-        if ((rc = mdb_cursor_get(cursor, &key, &data, d->allowDuplicates ? MDB_SET : MDB_FIRST)) == 0) {
-            numberOfRetrievedValues++;
-            if (resultHandler(QByteArray::fromRawData((char*)key.mv_data, key.mv_size), QByteArray::fromRawData((char*)data.mv_data, data.mv_size))) {
-                while ((rc = mdb_cursor_get(cursor, &key, &data, d->allowDuplicates ? MDB_NEXT_DUP : MDB_NEXT)) == 0) {
-                    numberOfRetrievedValues++;
-                    if (!resultHandler(QByteArray::fromRawData((char*)key.mv_data, key.mv_size), QByteArray::fromRawData((char*)data.mv_data, data.mv_size))) {
-                        break;
+    if (k.isEmpty() || d->allowDuplicates || findSubstringKeys) {
+        MDB_cursor_op op = d->allowDuplicates ? MDB_SET : MDB_FIRST;
+        if (findSubstringKeys) {
+            op = MDB_SET_RANGE;
+        }
+        if ((rc = mdb_cursor_get(cursor, &key, &data, op)) == 0) {
+            //The first lookup will find a key that is equal or greather than our key
+            if (QByteArray::fromRawData((char*)key.mv_data, key.mv_size).startsWith(k)) {
+                numberOfRetrievedValues++;
+                if (resultHandler(QByteArray::fromRawData((char*)key.mv_data, key.mv_size), QByteArray::fromRawData((char*)data.mv_data, data.mv_size))) {
+                    MDB_cursor_op nextOp = d->allowDuplicates ? MDB_NEXT_DUP : MDB_NEXT;
+                    while ((rc = mdb_cursor_get(cursor, &key, &data, nextOp)) == 0) {
+                        //Every consequent lookup simply iterates through the list
+                        if (QByteArray::fromRawData((char*)key.mv_data, key.mv_size).startsWith(k)) {
+                            numberOfRetrievedValues++;
+                            if (!resultHandler(QByteArray::fromRawData((char*)key.mv_data, key.mv_size), QByteArray::fromRawData((char*)data.mv_data, data.mv_size))) {
+                                break;
+                            }
+                        }
                     }
                 }
             }
@@ -226,6 +238,23 @@ int Storage::NamedDatabase::scan(const QByteArray &k,
 
     return numberOfRetrievedValues;
 }
+void Storage::NamedDatabase::findLatest(const QByteArray &uid,
+            const std::function<void(const QByteArray &key, const QByteArray &value)> &resultHandler,
+            const std::function<void(const Storage::Error &error)> &errorHandler) const
+{
+    QByteArray latestKey;
+    scan(uid, [&](const QByteArray &key, const QByteArray &value) -> bool {
+        latestKey = key;
+        return true;
+    },
+    errorHandler, true);
+
+    scan(latestKey, [=](const QByteArray &key, const QByteArray &value) -> bool {
+        resultHandler(key, value);
+        return false;
+    },
+    errorHandler);
+}
 
 
 
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