From 427b1d38d870e6876e10349b1081b56ff3390dec Mon Sep 17 00:00:00 2001
From: Minijackson <minijackson@riseup.net>
Date: Wed, 23 May 2018 17:20:34 +0200
Subject: Add and test findAllInRange for ranged lookups

---
 common/storage_lmdb.cpp | 62 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

(limited to 'common/storage_lmdb.cpp')

diff --git a/common/storage_lmdb.cpp b/common/storage_lmdb.cpp
index 5fb1d0f..bd9bdce 100644
--- a/common/storage_lmdb.cpp
+++ b/common/storage_lmdb.cpp
@@ -558,6 +558,68 @@ void DataStore::NamedDatabase::findLatest(const QByteArray &k, const std::functi
     return;
 }
 
+int DataStore::NamedDatabase::findAllInRange(const QByteArray &lowerBound, const QByteArray &upperBound,
+    const std::function<void(const QByteArray &key, const QByteArray &value)> &resultHandler,
+    const std::function<void(const DataStore::Error &error)> &errorHandler) const
+{
+    if (!d || !d->transaction) {
+        // Not an error. We rely on this to read nothing from non-existing databases.
+        return 0;
+    }
+
+    MDB_cursor *cursor;
+    if (int rc = mdb_cursor_open(d->transaction, d->dbi, &cursor)) {
+        // Invalid arguments can mean that the transaction doesn't contain the db dbi
+        Error error(d->name.toLatin1() + d->db, getErrorCode(rc),
+            QByteArray("Error during mdb_cursor_open: ") + QByteArray(mdb_strerror(rc)) +
+                ". Lower bound: " + lowerBound + " Upper bound: " + upperBound);
+        errorHandler ? errorHandler(error) : d->defaultErrorHandler(error);
+        return 0;
+    }
+
+    int numberOfRetrievedValues = 0;
+
+    MDB_val firstKey = { .mv_size = (size_t)lowerBound.size(), .mv_data = (void *)lowerBound.constData() },
+            idealLastKey = { .mv_size = (size_t)upperBound.size(), .mv_data = (void *)upperBound.constData() },
+            lastKey = idealLastKey, currentKey;
+    MDB_val reference;
+
+    // Find the last key past the range
+    int rc = mdb_cursor_get(cursor, &lastKey, &reference, MDB_SET_RANGE);
+
+    // If only equal, move forward one spot
+    if (rc == MDB_SUCCESS && mdb_cmp(d->transaction, d->dbi, &lastKey, &idealLastKey) == 0) {
+        rc = mdb_cursor_get(cursor, &lastKey, &reference, MDB_NEXT);
+    }
+
+    bool untilEnd = false;
+    if (rc != MDB_SUCCESS) {
+        // Nothing is greater than the upper bound, meaning search until the end
+        untilEnd = true;
+    }
+
+    // Find the first key in the range
+    rc = mdb_cursor_get(cursor, &firstKey, &reference, MDB_SET_RANGE);
+
+    if (rc != MDB_SUCCESS) {
+        // Nothing is greater or equal than the lower bound, meaning no result
+        return 0;
+    }
+
+    currentKey = firstKey;
+
+    do {
+        // If we have a stopping point and this is the stopping point
+        if (!untilEnd && mdb_cmp(d->transaction, d->dbi, &currentKey, &lastKey) == 0) {
+            break;
+        }
+
+        const auto currentBAKey = QByteArray::fromRawData((char *)currentKey.mv_data, currentKey.mv_size);
+        const auto currentBAValue = QByteArray::fromRawData((char *)reference.mv_data, reference.mv_size);
+        resultHandler(currentBAKey, currentBAValue);
+    } while (mdb_cursor_get(cursor, &currentKey, &reference, MDB_NEXT) == MDB_SUCCESS);
+}
+
 qint64 DataStore::NamedDatabase::getSize()
 {
     if (!d || !d->transaction) {
-- 
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