3 * DEBUG: section 20 Storage Manager Swapout Functions
4 * AUTHOR: Duane Wessels
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36 #include "StoreClient.h"
39 /* FIXME: Abstract the use of this more */
41 #include "MemObject.h"
42 #include "SquidConfig.h"
44 #include "StatCounters.h"
45 #include "store_log.h"
46 #include "swap_log_op.h"
48 static void storeSwapOutStart(StoreEntry
* e
);
49 static StoreIOState::STIOCB storeSwapOutFileClosed
;
50 static StoreIOState::STFNCB storeSwapOutFileNotify
;
52 // wrapper to cross C/C++ ABI boundary. xfree is extern "C" for libraries.
53 static void xfree_cppwrapper(void *x
)
58 /* start swapping object to disk */
60 storeSwapOutStart(StoreEntry
* e
)
62 MemObject
*mem
= e
->mem_obj
;
63 StoreIOState::Pointer sio
;
65 /* Build the swap metadata, so the filesystem will know how much
66 * metadata there is to store
68 debugs(20, 5, "storeSwapOutStart: Begin SwapOut '" << e
->url() << "' to dirno " <<
69 e
->swap_dirn
<< ", fileno " << std::hex
<< std::setw(8) << std::setfill('0') <<
70 std::uppercase
<< e
->swap_filen
);
71 e
->swap_status
= SWAPOUT_WRITING
;
72 /* If we start swapping out objects with OutOfBand Metadata,
73 * then this code needs changing
76 /* TODO: make some sort of data,size refcounted immutable buffer
77 * and stop fooling ourselves with "const char*" buffers.
80 // Create metadata now, possibly in vain: storeCreate needs swap_hdr_sz.
81 const char *buf
= e
->getSerialisedMetaData ();
84 /* Create the swap file */
85 generic_cbdata
*c
= new generic_cbdata(e
);
86 sio
= storeCreate(e
, storeSwapOutFileNotify
, storeSwapOutFileClosed
, c
);
89 e
->swap_status
= SWAPOUT_NONE
;
90 mem
->swapout
.decision
= MemObject::SwapOut::swImpossible
;
93 storeLog(STORE_LOG_SWAPOUTFAIL
, e
);
97 mem
->swapout
.sio
= sio
;
98 /* Don't lock until after create, or the replacement
99 * code might get confused */
102 /* Pick up the file number if it was assigned immediately */
103 e
->swap_filen
= mem
->swapout
.sio
->swap_filen
;
105 e
->swap_dirn
= mem
->swapout
.sio
->swap_dirn
;
107 /* write out the swap metadata */
108 storeIOWrite(mem
->swapout
.sio
, buf
, mem
->swap_hdr_sz
, 0, xfree_cppwrapper
);
112 storeSwapOutFileNotify(void *data
, int errflag
, StoreIOState::Pointer self
)
114 generic_cbdata
*c
= (generic_cbdata
*)data
;
115 StoreEntry
*e
= (StoreEntry
*)c
->data
;
116 MemObject
*mem
= e
->mem_obj
;
117 assert(e
->swap_status
== SWAPOUT_WRITING
);
119 assert(mem
->swapout
.sio
== self
);
120 assert(errflag
== 0);
121 assert(e
->swap_filen
< 0); // if this fails, call SwapDir::disconnect(e)
122 e
->swap_filen
= mem
->swapout
.sio
->swap_filen
;
123 e
->swap_dirn
= mem
->swapout
.sio
->swap_dirn
;
127 doPages(StoreEntry
*anEntry
)
129 MemObject
*mem
= anEntry
->mem_obj
;
132 // find the page containing the first byte we have not swapped out yet
134 mem
->data_hdr
.getBlockContainingLocation(mem
->swapout
.queue_offset
);
137 return; // wait for more data to become available
139 // memNodeWriteComplete() and absence of buffer offset math below
140 // imply that we always write from the very beginning of the page
141 assert(page
->start() == mem
->swapout
.queue_offset
);
144 * Get the length of this buffer. We are assuming(!) that the buffer
145 * length won't change on this buffer, or things are going to be very
146 * strange. I think that after the copy to a buffer is done, the buffer
147 * size should stay fixed regardless so that this code isn't confused,
148 * but we can look at this at a later date or whenever the code results
149 * in bad swapouts, whichever happens first. :-)
151 ssize_t swap_buf_len
= page
->nodeBuffer
.length
;
153 debugs(20, 3, "storeSwapOut: swap_buf_len = " << swap_buf_len
);
155 assert(swap_buf_len
> 0);
157 debugs(20, 3, "storeSwapOut: swapping out " << swap_buf_len
<< " bytes from " << mem
->swapout
.queue_offset
);
159 mem
->swapout
.queue_offset
+= swap_buf_len
;
161 storeIOWrite(mem
->swapout
.sio
,
162 mem
->data_hdr
.NodeGet(page
),
165 memNodeWriteComplete
);
167 /* the storeWrite() call might generate an error */
168 if (anEntry
->swap_status
!= SWAPOUT_WRITING
)
171 int64_t swapout_size
= mem
->endOffset() - mem
->swapout
.queue_offset
;
173 if (anEntry
->store_status
== STORE_PENDING
)
174 if (swapout_size
< SM_PAGE_SIZE
)
177 if (swapout_size
<= 0)
182 /* This routine is called every time data is sent to the client side.
183 * It's overhead is therefor, significant.
186 StoreEntry::swapOut()
191 // this flag may change so we must check even if we are swappingOut
192 if (EBIT_TEST(flags
, ENTRY_ABORTED
)) {
193 assert(EBIT_TEST(flags
, RELEASE_REQUEST
));
194 // StoreEntry::abort() already closed the swap out file, if any
195 // no trimming: data producer must stop production if ENTRY_ABORTED
199 const bool weAreOrMayBeSwappingOut
= swappingOut() || mayStartSwapOut();
201 Store::Root().maybeTrimMemory(*this, weAreOrMayBeSwappingOut
);
203 if (mem_obj
->swapout
.decision
!= MemObject::SwapOut::swPossible
)
204 return; // nothing else to do
206 // Aborted entries have STORE_OK, but swapoutPossible rejects them. Thus,
207 // store_status == STORE_OK below means we got everything we wanted.
209 debugs(20, 7, HERE
<< "storeSwapOut: mem->inmem_lo = " << mem_obj
->inmem_lo
);
210 debugs(20, 7, HERE
<< "storeSwapOut: mem->endOffset() = " << mem_obj
->endOffset());
211 debugs(20, 7, HERE
<< "storeSwapOut: swapout.queue_offset = " << mem_obj
->swapout
.queue_offset
);
213 if (mem_obj
->swapout
.sio
!= NULL
)
214 debugs(20, 7, "storeSwapOut: storeOffset() = " << mem_obj
->swapout
.sio
->offset() );
216 int64_t const lowest_offset
= mem_obj
->lowestMemReaderOffset();
218 debugs(20, 7, HERE
<< "storeSwapOut: lowest_offset = " << lowest_offset
);
220 #if SIZEOF_OFF_T <= 4
222 if (mem_obj
->endOffset() > 0x7FFF0000) {
223 debugs(20, DBG_CRITICAL
, "WARNING: preventing off_t overflow for " << url());
229 if (swap_status
== SWAPOUT_WRITING
)
230 assert(mem_obj
->inmem_lo
<= mem_obj
->objectBytesOnDisk() );
232 // buffered bytes we have not swapped out yet
233 const int64_t swapout_maxsize
= mem_obj
->availableForSwapOut();
234 assert(swapout_maxsize
>= 0);
235 debugs(20, 7, "storeSwapOut: swapout_size = " << swapout_maxsize
);
237 if (swapout_maxsize
== 0) { // swapped everything we got
238 if (store_status
== STORE_OK
) { // got everything we wanted
239 assert(mem_obj
->object_sz
>= 0);
240 swapOutFileClose(StoreIOState::wroteAll
);
242 // else need more data to swap out
246 if (store_status
== STORE_PENDING
) {
247 /* wait for a full block to write */
249 if (swapout_maxsize
< SM_PAGE_SIZE
)
253 * Wait until we are below the disk FD limit, only if the
254 * next server-side read won't be deferred.
256 if (storeTooManyDiskFilesOpen() && !checkDeferRead(-1))
260 /* Ok, we have stuff to swap out. Is there a swapout.sio open? */
261 if (swap_status
== SWAPOUT_NONE
) {
262 assert(mem_obj
->swapout
.sio
== NULL
);
263 assert(mem_obj
->inmem_lo
== 0);
264 storeSwapOutStart(this); // sets SwapOut::swImpossible on failures
267 if (mem_obj
->swapout
.sio
== NULL
)
272 if (mem_obj
->swapout
.sio
== NULL
)
273 /* oops, we're not swapping out any more */
276 if (store_status
== STORE_OK
) {
278 * If the state is STORE_OK, then all data must have been given
279 * to the filesystem at this point because storeSwapOut() is
280 * not going to be called again for this entry.
282 assert(mem_obj
->object_sz
>= 0);
283 assert(mem_obj
->endOffset() == mem_obj
->swapout
.queue_offset
);
284 swapOutFileClose(StoreIOState::wroteAll
);
289 StoreEntry::swapOutFileClose(int how
)
291 assert(mem_obj
!= NULL
);
292 debugs(20, 3, "storeSwapOutFileClose: " << getMD5Text() << " how=" << how
);
293 debugs(20, 3, "storeSwapOutFileClose: sio = " << mem_obj
->swapout
.sio
.getRaw());
295 if (mem_obj
->swapout
.sio
== NULL
)
298 storeClose(mem_obj
->swapout
.sio
, how
);
302 storeSwapOutFileClosed(void *data
, int errflag
, StoreIOState::Pointer self
)
304 generic_cbdata
*c
= (generic_cbdata
*)data
;
305 StoreEntry
*e
= (StoreEntry
*)c
->data
;
306 MemObject
*mem
= e
->mem_obj
;
307 assert(mem
->swapout
.sio
== self
);
308 assert(e
->swap_status
== SWAPOUT_WRITING
);
311 // if object_size is still unknown, the entry was probably aborted
312 if (errflag
|| e
->objectLen() < 0) {
313 debugs(20, 2, "storeSwapOutFileClosed: dirno " << e
->swap_dirn
<< ", swapfile " <<
314 std::hex
<< std::setw(8) << std::setfill('0') << std::uppercase
<<
315 e
->swap_filen
<< ", errflag=" << errflag
);
317 if (errflag
== DISK_NO_SPACE_LEFT
) {
318 /* FIXME: this should be handle by the link from store IO to
319 * Store, rather than being a top level API call.
321 e
->store()->diskFull();
325 if (e
->swap_filen
>= 0)
328 assert(e
->swap_status
== SWAPOUT_NONE
);
332 /* swapping complete */
333 debugs(20, 3, "storeSwapOutFileClosed: SwapOut complete: '" << e
->url() << "' to " <<
334 e
->swap_dirn
<< ", " << std::hex
<< std::setw(8) << std::setfill('0') <<
335 std::uppercase
<< e
->swap_filen
);
336 debugs(20, 5, HERE
<< "swap_file_sz = " <<
337 e
->objectLen() << " + " << mem
->swap_hdr_sz
);
339 e
->swap_file_sz
= e
->objectLen() + mem
->swap_hdr_sz
;
340 e
->swap_status
= SWAPOUT_DONE
;
341 e
->store()->swappedOut(*e
);
343 // XXX: For some Stores, it is pointless to re-check cachability here
344 // and it leads to double counts in store_check_cachable_hist. We need
345 // another way to signal a completed but failed swapout. Or, better,
346 // each Store should handle its own logging and LOG state setting.
347 if (e
->checkCachable()) {
348 storeLog(STORE_LOG_SWAPOUT
, e
);
349 storeDirSwapLog(e
, SWAP_LOG_ADD
);
352 ++statCounter
.swap
.outs
;
355 debugs(20, 3, "storeSwapOutFileClosed: " << __FILE__
<< ":" << __LINE__
);
356 mem
->swapout
.sio
= NULL
;
361 StoreEntry::mayStartSwapOut()
363 // must be checked in the caller
364 assert(!EBIT_TEST(flags
, ENTRY_ABORTED
));
365 assert(!swappingOut());
367 if (!Config
.cacheSwap
.n_configured
)
371 MemObject::SwapOut::Decision
&decision
= mem_obj
->swapout
.decision
;
373 // if we decided that swapout is not possible, do not repeat same checks
374 if (decision
== MemObject::SwapOut::swImpossible
) {
375 debugs(20, 3, HERE
<< " already rejected");
379 // if we decided that swapout is possible, do not repeat same checks
380 if (decision
== MemObject::SwapOut::swPossible
) {
381 debugs(20, 3, HERE
<< "already allowed");
385 // if we swapped out already, do not start over
386 if (swap_status
== SWAPOUT_DONE
) {
387 debugs(20, 3, HERE
<< "already did");
388 decision
= MemObject::SwapOut::swImpossible
;
392 if (!checkCachable()) {
393 debugs(20, 3, HERE
<< "not cachable");
394 decision
= MemObject::SwapOut::swImpossible
;
398 if (EBIT_TEST(flags
, ENTRY_SPECIAL
)) {
399 debugs(20, 3, HERE
<< url() << " SPECIAL");
400 decision
= MemObject::SwapOut::swImpossible
;
404 if (mem_obj
->inmem_lo
> 0) {
405 debugs(20, 3, "storeSwapOut: (inmem_lo > 0) imem_lo:" << mem_obj
->inmem_lo
);
406 decision
= MemObject::SwapOut::swImpossible
;
410 if (!mem_obj
->isContiguous()) {
411 debugs(20, 3, "storeSwapOut: not Contiguous");
412 decision
= MemObject::SwapOut::swImpossible
;
416 // check cache_dir max-size limit if all cache_dirs have it
417 if (store_maxobjsize
>= 0) {
418 // TODO: add estimated store metadata size to be conservative
420 // use guaranteed maximum if it is known
421 const int64_t expectedEnd
= mem_obj
->expectedReplySize();
422 debugs(20, 7, HERE
<< "expectedEnd = " << expectedEnd
);
423 if (expectedEnd
> store_maxobjsize
) {
424 debugs(20, 3, HERE
<< "will not fit: " << expectedEnd
<<
425 " > " << store_maxobjsize
);
426 decision
= MemObject::SwapOut::swImpossible
;
427 return false; // known to outgrow the limit eventually
430 // use current minimum (always known)
431 const int64_t currentEnd
= mem_obj
->endOffset();
432 if (currentEnd
> store_maxobjsize
) {
433 debugs(20, 3, HERE
<< "does not fit: " << currentEnd
<<
434 " > " << store_maxobjsize
);
435 decision
= MemObject::SwapOut::swImpossible
;
436 return false; // already does not fit and may only get bigger
439 // prevent final default swPossible answer for yet unknown length
440 if (expectedEnd
< 0 && store_status
!= STORE_OK
) {
441 const int64_t maxKnownSize
= mem_obj
->availableForSwapOut();
442 debugs(20, 7, HERE
<< "maxKnownSize= " << maxKnownSize
);
444 * NOTE: the store_maxobjsize here is the global maximum
445 * size of object cacheable in any of Squid cache stores
446 * both disk and memory stores.
448 * However, I am worried that this
449 * deferance may consume a lot of memory in some cases.
450 * Should we add an option to limit this memory consumption?
452 debugs(20, 5, HERE
<< "Deferring swapout start for " <<
453 (store_maxobjsize
- maxKnownSize
) << " bytes");
454 return true; // may still fit, but no final decision yet
458 decision
= MemObject::SwapOut::swPossible
;