[multimedia/kwave] libkwave: fixed performance bottleneck in sample storage subsystem

Git commit 3b5224c05490283cf1bf06c66f717efd1fdd86b5 by Thomas Eschenbacher.
Committed on 24/07/2026 at 19:14.
Pushed by eschenbacher into branch 'master'.

fixed performance bottleneck in sample storage subsystem

M  +23   -15   libkwave/SampleArray.cpp
M  +1    -1    libkwave/Stripe.cpp

https://invent.kde.org/multimedia/kwave/-/commit/3b5224c05490283cf1bf06c66f717efd1fdd86b5

diff --git a/libkwave/SampleArray.cpp b/libkwave/SampleArray.cpp
index 31e68751..1ac1bb2b 100644
--- a/libkwave/SampleArray.cpp
+++ b/libkwave/SampleArray.cpp
@@ -83,16 +83,21 @@ const sample_t & Kwave::SampleArray::operator [] (unsigned int index) const
 //***************************************************************************
 bool Kwave::SampleArray::resize(unsigned int size)
 {
+    const unsigned int current_size = this->size();
     if (!m_storage) return false;
-    if (size == m_storage->m_size) return true;
+    if (size == current_size) return true;
 
-    m_storage->resize(size);
-    if (size && (m_storage->m_size > size)) {
-        qWarning("Kwave::SampleArray::resize(): shrinking from %u to %u "
-                 "failed, keeping old memory", m_storage->m_size, size);
-        return true;
+    if (size == 0) {
+        m_storage = new(std::nothrow) SampleStorage;
+    } else {
+        m_storage->resize(size);
+        if (size && (this->size() > size)) {
+            qWarning("Kwave::SampleArray::resize(): shrinking from %u to %u "
+                    "failed, keeping old memory", current_size, size);
+            return true;
+        }
     }
-    return (m_storage->m_size == size);
+    return (this->size() == size);
 }
 
 //***************************************************************************
@@ -103,20 +108,22 @@ unsigned int Kwave::SampleArray::size() const
 
 //***************************************************************************
 Kwave::SampleArray::SampleStorage::SampleStorage()
-    :QSharedData()
+    :QSharedData(),
+     m_size(0),
+     m_data(nullptr)
 {
-    m_size     = 0;
-    m_data     = nullptr;
 }
 
 //***************************************************************************
 Kwave::SampleArray::SampleStorage::SampleStorage(const SampleStorage &other)
-    :QSharedData(other)
+    :QSharedData(other),
+     m_size(0),
+     m_data(nullptr)
 {
-    m_size     = 0;
-    m_data     = nullptr;
-
     if (other.m_size) {
+        // qDebug("SampleStorage - DEEP COPY");
+        // print_backtrace();
+
         m_data = static_cast<sample_t *>(
             ::malloc(other.m_size * sizeof(sample_t))
         );
@@ -130,7 +137,8 @@ Kwave::SampleArray::SampleStorage::SampleStorage(const SampleStorage &other)
 //***************************************************************************
 Kwave::SampleArray::SampleStorage::~SampleStorage()
 {
-    if (m_data) ::free(m_data);
+    ::free(m_data);
+    m_data = nullptr;
 }
 
 //***************************************************************************
diff --git a/libkwave/Stripe.cpp b/libkwave/Stripe.cpp
index 5e1d9c8f..807a0ec3 100644
--- a/libkwave/Stripe.cpp
+++ b/libkwave/Stripe.cpp
@@ -41,7 +41,7 @@ Kwave::Stripe::Stripe(Stripe &&other)
     :m_lock(), m_start(other.m_start), m_data(other.m_data)
 {
     other.m_start = 0;
-    other.m_data.resize(0);
+    other.resize(0);
 }
 
 //***************************************************************************