/*
- * $Id$
- *
* DEBUG: section 20 Storage Manager Swapout Functions
* AUTHOR: Duane Wessels
*
#include "squid.h"
#include "cbdata.h"
-#include "StoreClient.h"
+#include "globals.h"
#include "Store.h"
+#include "StoreClient.h"
/* FIXME: Abstract the use of this more */
#include "mem_node.h"
#include "MemObject.h"
-#include "SwapDir.h"
+#include "SquidConfig.h"
+#include "StatCounters.h"
+#include "store_log.h"
#include "swap_log_op.h"
+#include "SwapDir.h"
static void storeSwapOutStart(StoreEntry * e);
static StoreIOState::STIOCB storeSwapOutFileClosed;
static StoreIOState::STFNCB storeSwapOutFileNotify;
+// wrapper to cross C/C++ ABI boundary. xfree is extern "C" for libraries.
+static void xfree_cppwrapper(void *x)
+{
+ xfree(x);
+}
+
/* start swapping object to disk */
static void
storeSwapOutStart(StoreEntry * e)
/* If we start swapping out objects with OutOfBand Metadata,
* then this code needs changing
*/
+
+ /* TODO: make some sort of data,size refcounted immutable buffer
+ * and stop fooling ourselves with "const char*" buffers.
+ */
+
+ // Create metadata now, possibly in vain: storeCreate needs swap_hdr_sz.
+ const char *buf = e->getSerialisedMetaData ();
+ assert(buf);
+
/* Create the swap file */
generic_cbdata *c = new generic_cbdata(e);
sio = storeCreate(e, storeSwapOutFileNotify, storeSwapOutFileClosed, c);
if (sio == NULL) {
e->swap_status = SWAPOUT_NONE;
+ mem->swapout.decision = MemObject::SwapOut::swImpossible;
delete c;
+ xfree((char*)buf);
storeLog(STORE_LOG_SWAPOUTFAIL, e);
return;
}
e->swap_dirn = mem->swapout.sio->swap_dirn;
/* write out the swap metadata */
- /* TODO: make some sort of data,size refcounted immutable buffer
- * for use by this sort of function.
- */
- char const *buf = e->getSerialisedMetaData ();
-
- /* If we start swapping out with out of band metadata, this assert
- * will catch it - this code needs to be adjusted if that happens
- */
- assert (buf);
-
- storeIOWrite(mem->swapout.sio, buf, mem->swap_hdr_sz, 0, xfree);
+ storeIOWrite(mem->swapout.sio, buf, mem->swap_hdr_sz, 0, xfree_cppwrapper);
}
static void
assert(mem);
assert(mem->swapout.sio == self);
assert(errflag == 0);
+ assert(e->swap_filen < 0); // if this fails, call SwapDir::disconnect(e)
e->swap_filen = mem->swapout.sio->swap_filen;
e->swap_dirn = mem->swapout.sio->swap_dirn;
}
MemObject *mem = anEntry->mem_obj;
do {
- /*
- * Evil hack time.
- * We are paging out to disk in page size chunks. however, later on when
- * we update the queue position, we might not have a page (I *think*),
- * so we do the actual page update here.
- */
+ // find the page containing the first byte we have not swapped out yet
+ mem_node *page =
+ mem->data_hdr.getBlockContainingLocation(mem->swapout.queue_offset);
- if (mem->swapout.memnode == NULL) {
- /* We need to swap out the first page */
- mem->swapout.memnode = const_cast<mem_node *>(mem->data_hdr.start());
- } else {
- /* We need to swap out the next page */
- /* 20030636 RBC - we don't have ->next anymore.
- * But we do have the next location */
- mem->swapout.memnode = mem->data_hdr.getBlockContainingLocation (mem->swapout.memnode->end());
- }
+ if (!page)
+ return; // wait for more data to become available
+
+ // memNodeWriteComplete() and absence of buffer offset math below
+ // imply that we always write from the very beginning of the page
+ assert(page->start() == mem->swapout.queue_offset);
/*
* Get the length of this buffer. We are assuming(!) that the buffer
* but we can look at this at a later date or whenever the code results
* in bad swapouts, whichever happens first. :-)
*/
- ssize_t swap_buf_len = mem->swapout.memnode->nodeBuffer.length;
+ ssize_t swap_buf_len = page->nodeBuffer.length;
debugs(20, 3, "storeSwapOut: swap_buf_len = " << swap_buf_len);
mem->swapout.queue_offset += swap_buf_len;
storeIOWrite(mem->swapout.sio,
- mem->data_hdr.NodeGet(mem->swapout.memnode),
+ mem->data_hdr.NodeGet(page),
swap_buf_len,
-1,
memNodeWriteComplete);
} while (true);
}
-
/* This routine is called every time data is sent to the client side.
* It's overhead is therefor, significant.
*/
if (!mem_obj)
return;
- if (!swapoutPossible())
+ // this flag may change so we must check even if we are swappingOut
+ if (EBIT_TEST(flags, ENTRY_ABORTED)) {
+ assert(EBIT_TEST(flags, RELEASE_REQUEST));
+ // StoreEntry::abort() already closed the swap out file, if any
+ // no trimming: data producer must stop production if ENTRY_ABORTED
return;
+ }
+
+ const bool weAreOrMayBeSwappingOut = swappingOut() || mayStartSwapOut();
+
+ Store::Root().maybeTrimMemory(*this, weAreOrMayBeSwappingOut);
+
+ if (mem_obj->swapout.decision != MemObject::SwapOut::swPossible)
+ return; // nothing else to do
+
+ // Aborted entries have STORE_OK, but swapoutPossible rejects them. Thus,
+ // store_status == STORE_OK below means we got everything we wanted.
debugs(20, 7, HERE << "storeSwapOut: mem->inmem_lo = " << mem_obj->inmem_lo);
debugs(20, 7, HERE << "storeSwapOut: mem->endOffset() = " << mem_obj->endOffset());
if (mem_obj->swapout.sio != NULL)
debugs(20, 7, "storeSwapOut: storeOffset() = " << mem_obj->swapout.sio->offset() );
- int64_t swapout_maxsize = mem_obj->endOffset() - mem_obj->swapout.queue_offset;
-
- assert(swapout_maxsize >= 0);
-
int64_t const lowest_offset = mem_obj->lowestMemReaderOffset();
debugs(20, 7, HERE << "storeSwapOut: lowest_offset = " << lowest_offset);
- /*
- * Grab the swapout_size and check to see whether we're going to defer
- * the swapout based upon size
- */
- if ((store_status != STORE_OK) && (swapout_maxsize < store_maxobjsize)) {
- /*
- * NOTE: the store_maxobjsize here is the max of optional
- * max-size values from 'cache_dir' lines. It is not the
- * same as 'maximum_object_size'. By default, store_maxobjsize
- * will be set to -1. However, I am worried that this
- * deferance may consume a lot of memory in some cases.
- * It would be good to make this decision based on reply
- * content-length, rather than wait to accumulate huge
- * amounts of object data in memory.
- */
- debugs(20, 5, "storeSwapOut: Deferring starting swapping out");
- return;
- }
-
- trimMemory();
#if SIZEOF_OFF_T <= 4
if (mem_obj->endOffset() > 0x7FFF0000) {
- debugs(20, 0, "WARNING: preventing off_t overflow for " << url());
+ debugs(20, DBG_CRITICAL, "WARNING: preventing off_t overflow for " << url());
abort();
return;
}
if (swap_status == SWAPOUT_WRITING)
assert(mem_obj->inmem_lo <= mem_obj->objectBytesOnDisk() );
- if (!swapOutAble())
- return;
-
+ // buffered bytes we have not swapped out yet
+ const int64_t swapout_maxsize = mem_obj->availableForSwapOut();
+ assert(swapout_maxsize >= 0);
debugs(20, 7, "storeSwapOut: swapout_size = " << swapout_maxsize);
- if (swapout_maxsize == 0) {
- if (store_status == STORE_OK)
- swapOutFileClose();
-
- return; /* Nevermore! */
+ if (swapout_maxsize == 0) { // swapped everything we got
+ if (store_status == STORE_OK) { // got everything we wanted
+ assert(mem_obj->object_sz >= 0);
+ swapOutFileClose(StoreIOState::wroteAll);
+ }
+ // else need more data to swap out
+ return;
}
if (store_status == STORE_PENDING) {
if (swap_status == SWAPOUT_NONE) {
assert(mem_obj->swapout.sio == NULL);
assert(mem_obj->inmem_lo == 0);
-
- if (checkCachable())
- storeSwapOutStart(this);
- else
- return;
-
- /* ENTRY_CACHABLE will be cleared and we'll never get here again */
+ storeSwapOutStart(this); // sets SwapOut::swImpossible on failures
}
if (mem_obj->swapout.sio == NULL)
* to the filesystem at this point because storeSwapOut() is
* not going to be called again for this entry.
*/
+ assert(mem_obj->object_sz >= 0);
assert(mem_obj->endOffset() == mem_obj->swapout.queue_offset);
- swapOutFileClose();
+ swapOutFileClose(StoreIOState::wroteAll);
}
}
void
-StoreEntry::swapOutFileClose()
+StoreEntry::swapOutFileClose(int how)
{
assert(mem_obj != NULL);
- debugs(20, 3, "storeSwapOutFileClose: " << getMD5Text());
+ debugs(20, 3, "storeSwapOutFileClose: " << getMD5Text() << " how=" << how);
debugs(20, 3, "storeSwapOutFileClose: sio = " << mem_obj->swapout.sio.getRaw());
if (mem_obj->swapout.sio == NULL)
return;
- storeClose(mem_obj->swapout.sio);
+ storeClose(mem_obj->swapout.sio, how);
}
static void
assert(e->swap_status == SWAPOUT_WRITING);
cbdataFree(c);
- if (errflag) {
- debugs(20, 1, "storeSwapOutFileClosed: dirno " << e->swap_dirn << ", swapfile " <<
+ // if object_size is still unknown, the entry was probably aborted
+ if (errflag || e->objectLen() < 0) {
+ debugs(20, 2, "storeSwapOutFileClosed: dirno " << e->swap_dirn << ", swapfile " <<
std::hex << std::setw(8) << std::setfill('0') << std::uppercase <<
e->swap_filen << ", errflag=" << errflag);
- debugs(20, 1, "\t" << xstrerror());
if (errflag == DISK_NO_SPACE_LEFT) {
/* FIXME: this should be handle by the link from store IO to
storeConfigure();
}
- if (e->swap_filen > 0)
+ if (e->swap_filen >= 0)
e->unlink();
- e->swap_filen = -1;
-
- e->swap_dirn = -1;
-
- e->swap_status = SWAPOUT_NONE;
+ assert(e->swap_status == SWAPOUT_NONE);
e->releaseRequest();
} else {
debugs(20, 3, "storeSwapOutFileClosed: SwapOut complete: '" << e->url() << "' to " <<
e->swap_dirn << ", " << std::hex << std::setw(8) << std::setfill('0') <<
std::uppercase << e->swap_filen);
+ debugs(20, 5, HERE << "swap_file_sz = " <<
+ e->objectLen() << " + " << mem->swap_hdr_sz);
+
e->swap_file_sz = e->objectLen() + mem->swap_hdr_sz;
e->swap_status = SWAPOUT_DONE;
- e->store()->updateSize(e->swap_file_sz, 1);
+ e->store()->swappedOut(*e);
+ // XXX: For some Stores, it is pointless to re-check cachability here
+ // and it leads to double counts in store_check_cachable_hist. We need
+ // another way to signal a completed but failed swapout. Or, better,
+ // each Store should handle its own logging and LOG state setting.
if (e->checkCachable()) {
storeLog(STORE_LOG_SWAPOUT, e);
storeDirSwapLog(e, SWAP_LOG_ADD);
}
- statCounter.swap.outs++;
+ ++statCounter.swap.outs;
}
debugs(20, 3, "storeSwapOutFileClosed: " << __FILE__ << ":" << __LINE__);
e->unlock();
}
-/*
- * Is this entry a candidate for writing to disk?
- */
bool
-StoreEntry::swapOutAble() const
+StoreEntry::mayStartSwapOut()
{
- dlink_node *node;
+ // must be checked in the caller
+ assert(!EBIT_TEST(flags, ENTRY_ABORTED));
+ assert(!swappingOut());
- if (mem_obj->swapout.sio != NULL)
+ if (!Config.cacheSwap.n_configured)
+ return false;
+
+ assert(mem_obj);
+ MemObject::SwapOut::Decision &decision = mem_obj->swapout.decision;
+
+ // if we decided that swapout is not possible, do not repeat same checks
+ if (decision == MemObject::SwapOut::swImpossible) {
+ debugs(20, 3, HERE << " already rejected");
+ return false;
+ }
+
+ // if we decided that swapout is possible, do not repeat same checks
+ if (decision == MemObject::SwapOut::swPossible) {
+ debugs(20, 3, HERE << "already allowed");
return true;
+ }
- if (mem_obj->inmem_lo > 0)
+ // if we swapped out already, do not start over
+ if (swap_status == SWAPOUT_DONE) {
+ debugs(20, 3, HERE << "already did");
+ decision = MemObject::SwapOut::swImpossible;
return false;
+ }
- /*
- * If there are DISK clients, we must write to disk
- * even if its not cachable
- * RBC: Surely we should not create disk client on non cacheable objects?
- * therefore this should be an assert?
- * RBC 20030708: We can use disk to avoid mem races, so this shouldn't be
- * an assert.
- */
- for (node = mem_obj->clients.head; node; node = node->next) {
- if (((store_client *) node->data)->getType() == STORE_DISK_CLIENT)
- return true;
+ if (!checkCachable()) {
+ debugs(20, 3, HERE << "not cachable");
+ decision = MemObject::SwapOut::swImpossible;
+ return false;
}
- /* Don't pollute the disk with icons and other special entries */
- if (EBIT_TEST(flags, ENTRY_SPECIAL))
+ if (EBIT_TEST(flags, ENTRY_SPECIAL)) {
+ debugs(20, 3, HERE << url() << " SPECIAL");
+ decision = MemObject::SwapOut::swImpossible;
return false;
+ }
- if (!EBIT_TEST(flags, ENTRY_CACHABLE))
+ if (mem_obj->inmem_lo > 0) {
+ debugs(20, 3, "storeSwapOut: (inmem_lo > 0) imem_lo:" << mem_obj->inmem_lo);
+ decision = MemObject::SwapOut::swImpossible;
return false;
+ }
- if (!mem_obj->isContiguous())
+ if (!mem_obj->isContiguous()) {
+ debugs(20, 3, "storeSwapOut: not Contiguous");
+ decision = MemObject::SwapOut::swImpossible;
return false;
+ }
+
+ // check cache_dir max-size limit if all cache_dirs have it
+ if (store_maxobjsize >= 0) {
+ // TODO: add estimated store metadata size to be conservative
+
+ // use guaranteed maximum if it is known
+ const int64_t expectedEnd = mem_obj->expectedReplySize();
+ debugs(20, 7, HERE << "expectedEnd = " << expectedEnd);
+ if (expectedEnd > store_maxobjsize) {
+ debugs(20, 3, HERE << "will not fit: " << expectedEnd <<
+ " > " << store_maxobjsize);
+ decision = MemObject::SwapOut::swImpossible;
+ return false; // known to outgrow the limit eventually
+ }
+
+ // use current minimum (always known)
+ const int64_t currentEnd = mem_obj->endOffset();
+ if (currentEnd > store_maxobjsize) {
+ debugs(20, 3, HERE << "does not fit: " << currentEnd <<
+ " > " << store_maxobjsize);
+ decision = MemObject::SwapOut::swImpossible;
+ return false; // already does not fit and may only get bigger
+ }
+
+ // prevent final default swPossible answer for yet unknown length
+ if (expectedEnd < 0 && store_status != STORE_OK) {
+ const int64_t maxKnownSize = mem_obj->availableForSwapOut();
+ debugs(20, 7, HERE << "maxKnownSize= " << maxKnownSize);
+ /*
+ * NOTE: the store_maxobjsize here is the global maximum
+ * size of object cacheable in any of Squid cache stores
+ * both disk and memory stores.
+ *
+ * However, I am worried that this
+ * deferance may consume a lot of memory in some cases.
+ * Should we add an option to limit this memory consumption?
+ */
+ debugs(20, 5, HERE << "Deferring swapout start for " <<
+ (store_maxobjsize - maxKnownSize) << " bytes");
+ return true; // may still fit, but no final decision yet
+ }
+ }
+ decision = MemObject::SwapOut::swPossible;
return true;
}
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