}
static int prepare_resource_for_read(struct lookup_table_entry *lte
-
+
#ifdef WITH_NTFS_3G
, ntfs_inode **ni_ret
#endif
return 0;
}
+/*
+ * This function is executed by the main thread when the resources are being
+ * compressed in parallel. The main thread is in change of all reading of the
+ * uncompressed data and writing of the compressed data. The compressor threads
+ * *only* do compression from/to in-memory buffers.
+ *
+ * Each unit of work given to a compressor thread is up to MAX_CHUNKS_PER_MSG
+ * chunks of compressed data to compress, represented in a `struct message'.
+ * Each message is passed from the main thread to a worker thread through the
+ * res_to_compress_queue, and it is passed back through the
+ * compressed_res_queue.
+ */
static int main_writer_thread_proc(struct list_head *stream_list,
FILE *out_fp,
int out_ctype,
struct message msgs[queue_size];
ZERO_ARRAY(msgs);
+ // Initially, all the messages are available to use.
LIST_HEAD(available_msgs);
-
for (size_t i = 0; i < ARRAY_LEN(msgs); i++)
list_add(&msgs[i].list, &available_msgs);
-
+ // outstanding_resources is the list of resources that currently have
+ // had chunks sent off for compression.
+ //
+ // The first stream in outstanding_resources is the stream that is
+ // currently being written (cur_lte).
+ //
+ // The last stream in outstanding_resources is the stream that is
+ // currently being read and chunks fed to the compressor threads
+ // (next_lte).
+ //
+ // Depending on the number of threads and the sizes of the resource,
+ // the outstanding streams list may contain streams between cur_lte and
+ // next_lte that have all their chunks compressed or being compressed,
+ // but haven't been written yet.
+ //
+ LIST_HEAD(outstanding_resources);
struct list_head *next_resource = stream_list->next;
struct lookup_table_entry *next_lte = container_of(next_resource,
struct lookup_table_entry,
u64 next_chunk = 0;
u64 next_num_chunks = wim_resource_chunks(next_lte);
INIT_LIST_HEAD(&next_lte->msg_list);
+ list_add_tail(&next_lte->staging_list, &outstanding_resources);
+
+ // As in write_wim_resource(), each resource we read is checksummed.
SHA_CTX next_sha_ctx;
sha1_init(&next_sha_ctx);
-
u8 next_hash[SHA1_HASH_SIZE];
- // Resources owning chunks that have been sent off for compression
- LIST_HEAD(outstanding_resources);
-
- // Resources that are going to be written by the main thread
+ // Resources that don't need any chunks compressed are added to this
+ // list and written directly by the main thread.
LIST_HEAD(my_resources);
- list_add_tail(&next_lte->staging_list, &outstanding_resources);
-
struct lookup_table_entry *cur_lte = next_lte;
struct chunk_table *cur_chunk_tab = NULL;
struct lookup_table_entry *lte;
"and compressed data (%zu bytes needed)",
queue_size * MAX_CHUNKS_PER_MSG * WIM_CHUNK_SIZE * 2);
+ // Pre-allocate all the buffers that will be needed to do the chunk
+ // compression.
for (size_t i = 0; i < ARRAY_LEN(msgs); i++) {
for (size_t j = 0; j < MAX_CHUNKS_PER_MSG; j++) {
msgs[i].compressed_chunks[j] = MALLOC(WIM_CHUNK_SIZE);
// compressed.
while (!list_empty(&available_msgs) && next_lte != NULL) {
- wimlib_assert(next_chunk < next_num_chunks);
-
// Get a message from the available messages
// list
msg = container_of(available_msgs.next,
unsigned size = WIM_CHUNK_SIZE;
for (unsigned i = 0; i < msg->num_chunks; i++) {
+
+ // Read chunk @next_chunk of the stream into the
+ // message so that a compressor thread can
+ // compress it.
+
if (next_chunk == next_num_chunks - 1 &&
wim_resource_size(next_lte) % WIM_CHUNK_SIZE != 0)
{
size = wim_resource_size(next_lte) % WIM_CHUNK_SIZE;
}
+
DEBUG2("Read resource (size=%u, offset=%zu)",
size, next_chunk * WIM_CHUNK_SIZE);
// Advance to the next resource.
//
- // If the next resource needs no compression,
- // just write it with this thread (not now
- // though--- we could be in the middle of
- // writing another resource.) Keep doing this
- // until we either get to the end of the
- // resources list, or we get to a resource that
- // needs compression.
+ // If the next resource needs no compression, just write
+ // it with this thread (not now though--- we could be in
+ // the middle of writing another resource.) Keep doing
+ // this until we either get to the end of the resources
+ // list, or we get to a resource that needs compression.
while (1) {
if (next_resource == stream_list) {
}
// If there are no outstanding resources, there are no more
- // resources to compress.
+ // resources that need to be written.
if (list_empty(&outstanding_resources)) {
DEBUG("No outstanding resources! Done");
ret = 0;
DEBUG2("Complete msg (begin_chunk=%"PRIu64")", msg->begin_chunk);
if (msg->begin_chunk == 0) {
DEBUG2("Begin chunk tab");
- // This is the first set of chunks.
- // Leave space for the chunk table in
- // the output file.
+ // This is the first set of chunks. Leave space
+ // for the chunk table in the output file.
off_t cur_offset = ftello(out_fp);
if (cur_offset == -1) {
ret = WIMLIB_ERR_WRITE;
goto out;
}
- FREE(cur_chunk_tab);
- cur_chunk_tab = NULL;
ret = begin_wim_resource_chunk_tab(cur_lte,
out_fp,
cur_offset,
if (ret != 0)
goto out;
}
+
+ // Write the compressed chunks from the message.
ret = write_wim_chunks(msg, out_fp, cur_chunk_tab);
if (ret != 0)
goto out;
list_del(&msg->list);
+
+ // This message is available to use for different chunks
+ // now.
list_add(&msg->list, &available_msgs);
+ // Was this the last chunk of the stream? If so,
+ // finish it.
if (list_empty(&cur_lte->msg_list) &&
msg->begin_chunk + msg->num_chunks == cur_chunk_tab->num_chunks)
{
out_fp,
&res_csize);
if (ret != 0)
- return ret;
+ goto out;
+
cur_lte->output_resource_entry.size =
res_csize;
cur_lte->resource_entry.flags |
WIM_RESHDR_FLAG_COMPRESSED;
+ FREE(cur_chunk_tab);
+ cur_chunk_tab = NULL;
+
struct list_head *next = cur_lte->staging_list.next;
list_del(&cur_lte->staging_list);
staging_list);
}
+ // Since we just finished writing a stream,
+ // write any streams that have been added to the
+ // my_resources list for direct writing by the
+ // main thread (e.g. resources that don't need
+ // to be compressed because the desired
+ // compression type is the same as the previous
+ // compression type).
struct lookup_table_entry *tmp;
list_for_each_entry_safe(lte,
tmp,
}
while (num_available_msgs < ARRAY_LEN(msgs)) {
- msg = shared_queue_get(compressed_res_queue);
+ shared_queue_get(compressed_res_queue);
num_available_msgs++;
}
}
if (ret != 0)
goto out_destroy_res_to_compress_queue;
-
struct compressor_thread_params params;
params.res_to_compress_queue = &res_to_compress_queue;
params.compressed_res_queue = &compressed_res_queue;
wimlib_get_compression_type_string(out_ctype));
}
- if (compression_needed && total_size >= 0) { // XXX
+ if (compression_needed && total_size >= 1000000) {
return write_stream_list_parallel(stream_list, out_fp,
out_ctype, write_flags);
} else {
git://wimlib.net / wimlib / commitdiff