IOStream: allow subclasses of IOStream to influence how alloc() works
bug: 140112486
Currently, once one large transfer goes through, the buffer
is _permanently_ stuck at that size even if every other transfer
to the host is much smaller.
This CL makes that decision explicit, as a virtual method,
so that subclasses can decide on a better policy if it is ok for them.
This is especially important for shared memory ring-based transports
because it's preferred to keep the ring size at a constant small value.
Consistently large transfers will then either expand the ring too much
or permanently switch to a non-ring fallback.
Change-Id: Ia47ddb90c5521ee1f5918d77d492abc0f31ebfb8
diff --git a/host/include/libOpenglRender/IOStream.h b/host/include/libOpenglRender/IOStream.h
index ad82072..2f699bc 100644
--- a/host/include/libOpenglRender/IOStream.h
+++ b/host/include/libOpenglRender/IOStream.h
@@ -25,11 +25,15 @@
public:
IOStream(size_t bufSize) {
- m_buf = NULL;
+ m_iostreamBuf = NULL;
m_bufsize = bufSize;
m_free = 0;
}
+ virtual size_t idealAllocSize(size_t len) {
+ return m_bufsize < len ? len : m_bufsize;
+ }
+
virtual void *allocBuffer(size_t minSize) = 0;
virtual int commitBuffer(size_t size) = 0;
virtual const unsigned char *readFully( void *buf, size_t len) = 0;
@@ -39,22 +43,22 @@
virtual ~IOStream() {
- // NOTE: m_buf is 'owned' by the child class thus we expect it to be released by it
+ // NOTE: m_iostreamBuf is 'owned' by the child class thus we expect it to be released by it
}
virtual unsigned char *alloc(size_t len) {
- if (m_buf && len > m_free) {
+ if (m_iostreamBuf && len > m_free) {
if (flush() < 0) {
ERR("Failed to flush in alloc\n");
return NULL; // we failed to flush so something is wrong
}
}
- if (!m_buf || len > m_bufsize) {
- int allocLen = m_bufsize < len ? len : m_bufsize;
- m_buf = (unsigned char *)allocBuffer(allocLen);
- if (!m_buf) {
+ if (!m_iostreamBuf || len > m_bufsize) {
+ int allocLen = this->idealAllocSize(len);
+ m_iostreamBuf = (unsigned char *)allocBuffer(allocLen);
+ if (!m_iostreamBuf) {
ERR("Alloc (%u bytes) failed\n", allocLen);
return NULL;
}
@@ -63,7 +67,7 @@
unsigned char *ptr;
- ptr = m_buf + (m_bufsize - m_free);
+ ptr = m_iostreamBuf + (m_bufsize - m_free);
m_free -= len;
return ptr;
@@ -71,18 +75,18 @@
virtual int flush() {
- if (!m_buf || m_free == m_bufsize) return 0;
+ if (!m_iostreamBuf || m_free == m_bufsize) return 0;
int stat = commitBuffer(m_bufsize - m_free);
- m_buf = NULL;
+ m_iostreamBuf = NULL;
m_free = 0;
return stat;
}
const unsigned char *readback(void *buf, size_t len) {
- if (m_buf && m_free != m_bufsize) {
+ if (m_iostreamBuf && m_free != m_bufsize) {
size_t size = m_bufsize - m_free;
- m_buf = NULL;
+ m_iostreamBuf = NULL;
m_free = 0;
return commitBufferAndReadFully(size, buf, len);
}
@@ -93,7 +97,7 @@
private:
- unsigned char *m_buf;
+ unsigned char *m_iostreamBuf;
size_t m_bufsize;
size_t m_free;
};
