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[slam] Request all remaining blocks if we run out of space for the blocklist 

In a SLAM NACK packet, if we run out of space to represent the
missing-block list, then indicate all remaining blocks as missing.
This avoids the need to wait for the one-second timeout before
receiving the blocks that otherwise wouldn't have been requested due
to running out of space.
This commit is contained in:
Michael Brown 2008-06-10 12:30:43 +01:00
parent 1e5c2d48cb
commit 2456b9b4ba
1 changed files with 41 additions and 22 deletions
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63
src/net/udp/slam.c
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@ -191,14 +191,14 @@ static void slam_finished ( struct slam_request *slam, int rc ) {
* @v slam SLAM request
* @v iobuf I/O buffer
* @v value Value to add
* @ret rc Return status code
* @v reserved Length of reserved space at end of buffer
* @ret len Length of value, or negative error.
*
* Adds a variable-length value to the end of an I/O buffer. Will
* refuse to use the last byte of the I/O buffer; this is to allow
* space for the terminating NUL.
* Adds a variable-length value to the end of an I/O buffer.
*/
static int slam_put_value ( struct slam_request *slam,
struct io_buffer *iobuf, unsigned long value ) {
struct io_buffer *iobuf, unsigned long value,
size_t reserved ) {
uint8_t *data;
size_t len;
unsigned int i;
@ -207,7 +207,7 @@ static int slam_put_value ( struct slam_request *slam,
* leave at least one byte in the I/O buffer.
*/
len = ( ( flsl ( value ) + 10 ) / 8 );
if ( len >= iob_tailroom ( iobuf ) ) {
if ( ( len + reserved ) > iob_tailroom ( iobuf ) ) {
DBGC2 ( slam, "SLAM %p cannot add %d-byte value\n",
slam, len );
return -ENOBUFS;
@ -227,7 +227,7 @@ static int slam_put_value ( struct slam_request *slam,
*data |= ( len << 5 );
assert ( value == 0 );
return 0;
return len;
}
/**
@ -239,13 +239,16 @@ static int slam_put_value ( struct slam_request *slam,
*/
static int slam_build_block_list ( struct slam_request *slam,
struct io_buffer *iobuf ) {
unsigned int block;
unsigned int block_count;
unsigned long block;
unsigned long block_count;
int block_present;
int last_block_present;
int len;
size_t last_len = 0;
unsigned long last_block_count = 0;
int rc;
DBGC ( slam, "SLAM %p asking for ", slam );
DBGC ( slam, "SLAM %p asking for", slam );
/* Walk bitmap to construct list */
block_count = 0;
@ -253,27 +256,43 @@ static int slam_build_block_list ( struct slam_request *slam,
for ( block = 0 ; block < slam->num_blocks ; block++ ) {
block_present = ( !! bitmap_test ( &slam->bitmap, block ) );
if ( block_present != last_block_present ) {
if ( ( rc = slam_put_value ( slam, iobuf,
block_count ) ) != 0 ) {
DBGC ( slam, "...\n" );
return rc;
}
DBGC ( slam, "%c%d",
if ( ( len = slam_put_value ( slam, iobuf, block_count,
( sizeof ( block ) + 1 ) ) ) < 0 )
goto truncated;
DBGC ( slam, "%c%ld",
( last_block_present ? ' ' : '-' ),
( last_block_present ? block : block - 1 ) );
block_count = 0;
last_len = len;
last_block_count = block_count;
last_block_present = block_present;
block_count = 0;
}
block_count++;
}
if ( ( rc = slam_put_value ( slam, iobuf, block_count ) ) != 0 ) {
DBGC ( slam, "...\n" );
return rc;
}
DBGC ( slam, "%c%d\n", ( last_block_present ? ' ' : '-' ),
if ( ( len = slam_put_value ( slam, iobuf, block_count,
( sizeof ( block ) + 1 ) ) ) < 0 )
goto truncated;
DBGC ( slam, "%c%ld\n", ( last_block_present ? ' ' : '-' ),
( last_block_present ? block : block - 1 ) );
return 0;
truncated:
rc = len;
block -= block_count;
assert ( last_len != 0 ); /* Cannot truncate on first entry */
if ( last_block_present ) {
/* Replace last missing-blocks number */
DBGC ( slam, "#" );
iob_unput ( iobuf, last_len );
block -= last_block_count;
}
/* Report all remaining blocks as missing */
block_count = ( slam->num_blocks - block );
DBGC ( slam, "-%ld\n", ( slam->num_blocks - 1 ) );
len = slam_put_value ( slam, iobuf, block_count, 1 );
assert ( len > 0 );
return rc;
}
/**