X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=buffer_tree.c;h=dfecf10a24906f2e165ed9368f69c23e99f6e291;hp=7b3355a28b98aa601431029c83063aac016d2d9d;hb=e3acf84bf26f2730575624b1a1d3979d84272427;hpb=e4713d70469e7ca1afd8e8b9a3e67c3764cf3933

diff --git a/buffer_tree.c b/buffer_tree.c
index 7b3355a2..dfecf10a 100644
--- a/buffer_tree.c
+++ b/buffer_tree.c
@@ -6,13 +6,27 @@
 #include "string.h"
 #include "buffer_tree.h"
 #include "error.h"
+#include "sched.h"
 
+struct btr_pool {
+	char *name;
+	char *area_start;
+	char *area_end;
+	char *rhead;
+	char *whead;
+};
+
+enum btr_buffer_flags {
+	/* changes the way the buffer is deallocated */
+	BTR_BF_BTR_POOL = 1,
+};
 
 struct btr_buffer {
 	char *buf;
 	size_t size;
 	/** The number of references to this buffer. */
 	int refcount;
+	struct btr_pool *pool;
 };
 
 struct btr_buffer_reference {
@@ -20,6 +34,7 @@ struct btr_buffer_reference {
 	size_t consumed;
 	/* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
 	struct list_head node;
+	size_t wrap_count;
 };
 
 struct btr_node {
@@ -29,6 +44,8 @@ struct btr_node {
 	struct list_head node;
 	/* The children nodes of this btr node are linked together in a list. */
 	struct list_head children;
+	/* Time of first data transfer. */
+	struct timeval start;
 	/**
 	 * The input queue is a list of references to btr buffers. Each item on
 	 * the list represents an input buffer which has not been completely
@@ -39,15 +56,119 @@ struct btr_node {
 	void *context;
 };
 
+struct btr_pool *btr_pool_new(const char *name, size_t area_size)
+{
+	struct btr_pool *btrp;
+
+	PARA_INFO_LOG("%s, %zu bytes\n", name, area_size);
+	btrp = para_malloc(sizeof(*btrp));
+	btrp->area_start = para_malloc(area_size);
+	btrp->area_end = btrp->area_start + area_size;
+	btrp->rhead = btrp->area_start;
+	btrp->whead = btrp->area_start;
+	btrp->name = para_strdup(name);
+	return btrp;
+}
+
+/* whead = NULL means area full */
+
+void btr_pool_free(struct btr_pool *btrp)
+{
+	if (!btrp)
+		return;
+	free(btrp->area_start);
+	free(btrp->name);
+	free(btrp);
+}
+
+size_t btr_pool_size(struct btr_pool *btrp)
+{
+	return btrp->area_end - btrp->area_start;
+}
+
+size_t btr_pool_filled(struct btr_pool *btrp)
+{
+	if (!btrp->whead)
+		return btr_pool_size(btrp);
+	if (btrp->rhead <= btrp->whead)
+		return  btrp->whead - btrp->rhead;
+	return btr_pool_size(btrp) - (btrp->rhead - btrp->whead);
+}
+
+size_t btr_pool_unused(struct btr_pool *btrp)
+{
+	return btr_pool_size(btrp) - btr_pool_filled(btrp);
+}
+
+size_t btr_pool_available(struct btr_pool *btrp)
+{
+	if (!btrp->whead)
+		return 0;
+	if (btrp->rhead <= btrp->whead)
+		return btrp->area_end - btrp->whead;
+	return btrp->rhead - btrp->whead;
+}
+
+size_t btr_pool_get_buffer(struct btr_pool *btrp, char **result)
+{
+	if (result)
+		*result = btrp->whead;
+	return btr_pool_available(btrp);
+}
+
+void btr_pool_allocate(struct btr_pool *btrp, size_t size)
+{
+	char *end;
+
+	if (size == 0)
+		return;
+	//PARA_CRIT_LOG("filled: %zu, alloc %zu\n", btr_pool_filled(btrp), size);
+	assert(size <= btr_pool_available(btrp));
+	end = btrp->whead + size;
+	assert(end <= btrp->area_end);
+
+	if (end == btrp->area_end) {
+		PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp->name);
+		end = btrp->area_start;
+	}
+	if (end == btrp->rhead) {
+		PARA_DEBUG_LOG("btrp buffer full\n");
+		end = NULL; /* buffer full */
+	}
+	btrp->whead = end;
+	//PARA_CRIT_LOG("filled: %zu\n", btr_pool_filled(btrp));
+}
+
+static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
+{
+	char *end = btrp->rhead + size;
+
+	//PARA_CRIT_LOG("filled: %zu, dealloc %zu\n", btr_pool_filled(btrp), size);
+	if (size == 0)
+		return;
+	assert(end <= btrp->area_end);
+	assert(size <= btr_pool_filled(btrp));
+	if (end == btrp->area_end)
+		end = btrp->area_start;
+	if (!btrp->whead)
+		btrp->whead = btrp->rhead;
+	btrp->rhead = end;
+	if (btrp->rhead == btrp->whead)
+		btrp->rhead = btrp->whead = btrp->area_start;
+	//PARA_CRIT_LOG("filled: %zu\n", btr_pool_filled(btrp));
+}
+
 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
 	&((_btrn)->children), node)
+#define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
+	list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
 
 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
 	list_for_each_entry((_br), &(_btrn)->input_queue, node)
 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
 	list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
 
-struct btr_node *btr_new_node(char *name, struct btr_node *parent,
+struct btr_node *btr_new_node(const char *name, struct btr_node *parent,
 		btr_command_handler handler, void *context)
 {
 	struct btr_node *btrn = para_malloc(sizeof(*btrn));
@@ -56,28 +177,50 @@ struct btr_node *btr_new_node(char *name, struct btr_node *parent,
 	btrn->parent = parent;
 	btrn->execute = handler;
 	btrn->context = context;
+	btrn->start.tv_sec = 0;
+	btrn->start.tv_usec = 0;
 	if (parent)
 		list_add_tail(&btrn->node, &parent->children);
 	INIT_LIST_HEAD(&btrn->children);
 	INIT_LIST_HEAD(&btrn->input_queue);
+	if (parent)
+		PARA_INFO_LOG("added %s as child of %s\n", name, parent->name);
+	else
+		PARA_INFO_LOG("added %s as btr root\n", name);
 	return btrn;
 }
 
 /*
  * Allocate a new btr buffer.
  *
- * The freshly allocated buffer will have a zero refcount.
+ * The freshly allocated buffer will have a zero refcount and will
+ * not be associated with a btr pool.
  */
 static struct btr_buffer *new_btrb(char *buf, size_t size)
 {
-	struct btr_buffer *btrb = para_malloc(sizeof(*btrb));
+	struct btr_buffer *btrb = para_calloc(sizeof(*btrb));
 
 	btrb->buf = buf;
 	btrb->size = size;
-	btrb->refcount = 0;
 	return btrb;
 }
 
+static void dealloc_buffer(struct btr_buffer *btrb)
+{
+	if (btrb->pool)
+		btr_pool_deallocate(btrb->pool, btrb->size);
+	else
+		free(btrb->buf);
+}
+
+static struct btr_buffer_reference *get_first_input_br(struct btr_node *btrn)
+{
+	if (list_empty(&btrn->input_queue))
+		return NULL;
+	return list_first_entry(&btrn->input_queue,
+		struct btr_buffer_reference, node);
+}
+
 /*
  * Deallocate the reference, release the resources if refcount drops to zero.
  */
@@ -90,7 +233,7 @@ static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
 	free(br);
 	btrb->refcount--;
 	if (btrb->refcount == 0) {
-		free(btrb->buf);
+		dealloc_buffer(btrb);
 		free(btrb);
 	}
 }
@@ -100,12 +243,16 @@ static void add_btrb_to_children(struct btr_buffer *btrb,
 {
 	struct btr_node *ch;
 
+	if (btrn->start.tv_sec == 0)
+		btrn->start = *now;
 	FOR_EACH_CHILD(ch, btrn) {
-		struct btr_buffer_reference *br = para_malloc(sizeof(*br));
+		struct btr_buffer_reference *br = para_calloc(sizeof(*br));
 		br->btrb = btrb;
 		br->consumed = consumed;
 		list_add_tail(&br->node, &ch->input_queue);
 		btrb->refcount++;
+		if (ch->start.tv_sec == 0)
+			ch->start = *now;
 	}
 }
 
@@ -113,10 +260,54 @@ void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
 {
 	struct btr_buffer *btrb;
 
+	assert(size != 0);
+	if (list_empty(&btrn->children)) {
+		free(buf);
+		return;
+	}
 	btrb = new_btrb(buf, size);
 	add_btrb_to_children(btrb, btrn, 0);
 }
 
+void btr_add_output_pool(struct btr_pool *btrp, size_t size,
+		struct btr_node *btrn)
+{
+	struct btr_buffer *btrb;
+	char *buf;
+	size_t avail;
+
+	assert(size != 0);
+	if (list_empty(&btrn->children))
+		return;
+	avail = btr_pool_get_buffer(btrp, &buf);
+	assert(avail >= size);
+	btr_pool_allocate(btrp, size);
+	btrb = new_btrb(buf, size);
+	btrb->pool = btrp;
+	add_btrb_to_children(btrb, btrn, 0);
+}
+
+void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
+	struct btr_node *btrn)
+{
+	char *buf;
+	size_t sz, copy;
+
+	if (n == 0)
+		return;
+	assert(n <= btr_pool_unused(btrp));
+	sz = btr_pool_get_buffer(btrp, &buf);
+	copy = PARA_MIN(sz, n);
+	memcpy(buf, src, copy);
+	btr_add_output_pool(btrp, copy, btrn);
+	if (copy == n)
+		return;
+	sz = btr_pool_get_buffer(btrp, &buf);
+	assert(sz >= n - copy);
+	memcpy(buf, src + copy, n - copy);
+	btr_add_output_pool(btrp, n - copy, btrn);
+}
+
 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
 {
 	add_btrb_to_children(br->btrb, btrn, br->consumed);
@@ -131,6 +322,17 @@ void btr_pushdown(struct btr_node *btrn)
 		btr_pushdown_br(br, btrn);
 }
 
+int btr_pushdown_one(struct btr_node *btrn)
+{
+	struct btr_buffer_reference *br;
+
+	if (list_empty(&btrn->input_queue))
+		return 0;
+	br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
+	btr_pushdown_br(br, btrn);
+	return 1;
+}
+
 /* Return true if this node has no children. */
 bool btr_no_children(struct btr_node *btrn)
 {
@@ -156,32 +358,98 @@ static inline size_t br_available_bytes(struct btr_buffer_reference *br)
 
 size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
 {
-	*buf = br->btrb->buf + br->consumed;
+	if (buf)
+		*buf = br->btrb->buf + br->consumed;
 	return br_available_bytes(br);
 }
 
+/**
+ * \return zero if the input buffer queue is empty.
+ */
 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
 {
 	struct btr_buffer_reference *br;
+	char *buf, *result = NULL;
+	size_t sz, rv = 0;
 
-	if (list_empty(&btrn->input_queue)) {
-		*bufp = NULL;
-		return 0;
+	FOR_EACH_BUFFER_REF(br, btrn) {
+		sz = btr_get_buffer_by_reference(br, &buf);
+		if (!result) {
+			result = buf;
+			rv = sz;
+			if (!br->btrb->pool)
+				break;
+			continue;
+		}
+		if (!br->btrb->pool)
+			break;
+		if (result + rv != buf) {
+			PARA_DEBUG_LOG("%s: pool merge impossible: %p != %p\n",
+				btrn->name, result + rv, buf);
+			break;
+		}
+//		PARA_CRIT_LOG("%s: inplace merge (%zu, %zu)->%zu\n", btrn->name,
+//			rv, sz, rv + sz);
+//		PARA_CRIT_LOG("%s: inplace merge %p (%zu)\n", btrn->name,
+//			result, sz);
+		rv += sz;
 	}
-	br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
-	return btr_get_buffer_by_reference(br, bufp);
+	if (bufp)
+		*bufp = result;
+	return rv;
 }
 
 void btr_consume(struct btr_node *btrn, size_t numbytes)
 {
-	struct btr_buffer_reference *br;
+	struct btr_buffer_reference *br, *tmp;
+	size_t sz;
 
-	assert(!list_empty(&btrn->input_queue));
-	br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
-	assert(br->consumed + numbytes <= br->btrb->size);
-	br->consumed += numbytes;
-	if (br->consumed == br->btrb->size)
-		btr_drop_buffer_reference(br);
+	if (numbytes == 0)
+		return;
+	br = get_first_input_br(btrn);
+	assert(br);
+
+	//PARA_CRIT_LOG("wrap count: %zu\n", br->wrap_count);
+	if (br->wrap_count == 0) {
+		/*
+		 * No wrap buffer. Drop buffer references whose buffer
+		 * has been fully used. */
+		FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) {
+			if (br->consumed + numbytes <= br->btrb->size) {
+				br->consumed += numbytes;
+				if (br->consumed == br->btrb->size)
+					btr_drop_buffer_reference(br);
+				return;
+			}
+			numbytes -= br->btrb->size - br->consumed;
+			btr_drop_buffer_reference(br);
+		}
+		assert(true);
+	}
+	/*
+
+	We have a wrap buffer, consume from it. If in total,
+	i.e. including previous calls to brt_consume(), less than
+	wrap_count has been consumed, there's nothing more we can do.
+
+	Otherwise we drop the wrap buffer and consume from subsequent
+	buffers of the input queue the correct amount of bytes. This
+	is the total number of bytes that have been consumed from the
+	wrap buffer.
+*/
+	PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
+		br_available_bytes(br));
+
+	assert(numbytes <= br_available_bytes(br));
+	if (br->consumed + numbytes < br->wrap_count) {
+		br->consumed += numbytes;
+		return;
+	}
+	PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br->btrb->size);
+	/* get rid of the wrap buffer */
+	sz = br->consumed + numbytes;
+	btr_drop_buffer_reference(br);
+	return btr_consume(btrn, sz);
 }
 
 static void flush_input_queue(struct btr_node *btrn)
@@ -191,20 +459,26 @@ static void flush_input_queue(struct btr_node *btrn)
 		btr_drop_buffer_reference(br);
 }
 
-void btr_del_node(struct btr_node *btrn)
+void btr_free_node(struct btr_node *btrn)
+{
+	if (!btrn)
+		return;
+	free(btrn->name);
+	free(btrn);
+}
+
+void btr_remove_node(struct btr_node *btrn)
 {
 	struct btr_node *ch;
 
 	if (!btrn)
 		return;
-	PARA_NOTICE_LOG("deleting %s\n", btrn->name);
+	PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn->name);
 	FOR_EACH_CHILD(ch, btrn)
 		ch->parent = NULL;
 	flush_input_queue(btrn);
 	if (btrn->parent)
 		list_del(&btrn->node);
-	free(btrn->name);
-	free(btrn);
 }
 
 size_t btr_get_input_queue_size(struct btr_node *btrn)
@@ -219,22 +493,23 @@ size_t btr_get_input_queue_size(struct btr_node *btrn)
 	return size;
 }
 
-int btr_splice_out_node(struct btr_node *btrn)
+void btr_splice_out_node(struct btr_node *btrn)
 {
-	struct btr_node *ch;
+	struct btr_node *ch, *tmp;
 
-	if (!btrn)
-		return -ERRNO_TO_PARA_ERROR(EINVAL);
-	if (btr_get_input_queue_size(btrn) != 0)
-		return -ERRNO_TO_PARA_ERROR(EINVAL);
+	assert(btrn);
 	PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
+	btr_pushdown(btrn);
 	if (btrn->parent)
 		list_del(&btrn->node);
-	FOR_EACH_CHILD(ch, btrn)
+	FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
+		PARA_INFO_LOG("parent(%s): %s\n", ch->name,
+			btrn->parent? btrn->parent->name : "NULL");
 		ch->parent = btrn->parent;
-	free(btrn->name);
-	free(btrn);
-	return 1;
+		if (btrn->parent)
+			list_move(&ch->node, &btrn->parent->children);
+	}
+	assert(list_empty(&btrn->children));
 }
 
 /**
@@ -269,16 +544,20 @@ int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
 
 	for (; btrn; btrn = btrn->parent) {
 		struct btr_node *parent = btrn->parent;
-		PARA_CRIT_LOG("parent: %p\n", parent);
 		if (!parent)
 			return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 		if (!parent->execute)
 			continue;
+		PARA_INFO_LOG("parent: %s, cmd: %s\n", parent->name, command);
 		ret = parent->execute(parent, command, value_result);
 		if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
 			continue;
 		if (ret < 0)
 			return ret;
+		if (value_result && *value_result)
+			PARA_NOTICE_LOG("%s(%s): %s\n", command, parent->name,
+				*value_result);
+		return 1;
 	}
 	return -ERRNO_TO_PARA_ERROR(ENOTSUP);
 }
@@ -287,3 +566,238 @@ void *btr_context(struct btr_node *btrn)
 {
 	return btrn->context;
 }
+
+static bool need_buffer_pool_merge(struct btr_node *btrn)
+{
+	struct btr_buffer_reference *br = get_first_input_br(btrn);
+
+	if (!br)
+		return false;
+	if (br->wrap_count != 0)
+		return true;
+	if (br->btrb->pool)
+		return true;
+	return false;
+}
+
+static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
+{
+	struct btr_buffer_reference *br, *wbr;
+	int num_refs; /* including wrap buffer */
+	char *buf, *buf1, *buf2 = NULL;
+	size_t sz, sz1, sz2 = 0, wsz;
+
+	if (list_empty(&btrn->input_queue))
+		return;
+
+	num_refs = 0;
+	FOR_EACH_BUFFER_REF(br, btrn) {
+		num_refs++;
+		sz = btr_get_buffer_by_reference(br, &buf);
+		if (br->wrap_count != 0) {
+			assert(!wbr);
+			assert(num_refs == 1);
+			wbr = br;
+			if (sz >= dest_size)
+				return;
+			continue;
+		}
+		if (!buf1) {
+			buf1 = buf;
+			sz1 = sz;
+			goto next;
+		}
+		if (buf1 + sz1 == buf) {
+			sz1 += sz;
+			goto next;
+		}
+		if (!buf2) {
+			buf2 = buf;
+			sz2 = sz;
+			goto next;
+		}
+		assert(buf2 + sz2 == buf);
+		sz2 += sz;
+next:
+		if (sz1 + sz2 >= dest_size)
+			break;
+	}
+	/*
+	 * If the second buffer is large, we only take the first part of it to
+	 * avoid having to memcpy() huge buffers.
+	 */
+	sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
+	if (!wbr) {
+		assert(buf1);
+		if (!buf2) /* nothing to do */
+			return;
+		/* Make a new wrap buffer combining buf1 and buf2. */
+		sz = sz1 + sz2;
+		buf = para_malloc(sz);
+		PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
+			buf1, sz1, buf2, sz2, buf, sz);
+		memcpy(buf, buf1, sz1);
+		memcpy(buf + sz1, buf2, sz2);
+		br = para_calloc(sizeof(*br));
+		br->btrb = new_btrb(buf, sz);
+		br->btrb->refcount = 1;
+		br->consumed = 0;
+		/* This is a wrap buffer */
+		br->wrap_count = sz1;
+		para_list_add(&br->node, &btrn->input_queue);
+		return;
+	}
+	/*
+	 * We already have a wrap buffer, but it is too small. It might be
+	 * partially used.
+	 */
+	wsz = br_available_bytes(wbr);
+	if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
+		return;
+	assert(buf1 && buf2);
+	sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
+	wbr->btrb->size += sz;
+	PARA_DEBUG_LOG("increasing wrap buffer to %zu\n", wbr->btrb->size);
+	wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
+	/* copy the new data to the end of the reallocated buffer */
+	assert(sz2 >= sz);
+	memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
+}
+
+/**
+ * Merge the first two input buffers into one.
+ *
+ * This is a quite expensive operation.
+ *
+ * \return The number of buffers that have been available (zero, one or two).
+ */
+static int merge_input(struct btr_node *btrn)
+{
+	struct btr_buffer_reference *brs[2], *br;
+	char *bufs[2], *buf;
+	size_t szs[2], sz;
+	int i;
+
+	if (list_empty(&btrn->input_queue))
+		return 0;
+	if (list_is_singular(&btrn->input_queue))
+		return 1;
+	i = 0;
+	/* get references to the first two buffers */
+	FOR_EACH_BUFFER_REF(br, btrn) {
+		brs[i] = br;
+		szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
+		i++;
+		if (i == 2)
+			break;
+	}
+	/* make a new btrb that combines the two buffers and a br to it. */
+	sz = szs[0] + szs[1];
+	buf = para_malloc(sz);
+	PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
+		btrn->name, szs[0], szs[1], sz);
+	memcpy(buf, bufs[0], szs[0]);
+	memcpy(buf + szs[0], bufs[1], szs[1]);
+
+	br = para_calloc(sizeof(*br));
+	br->btrb = new_btrb(buf, sz);
+	br->btrb->refcount = 1;
+
+	/* replace the first two refs by the new one */
+	btr_drop_buffer_reference(brs[0]);
+	btr_drop_buffer_reference(brs[1]);
+	para_list_add(&br->node, &btrn->input_queue);
+	return 2;
+}
+
+void btr_merge(struct btr_node *btrn, size_t dest_size)
+{
+	if (need_buffer_pool_merge(btrn))
+		return merge_input_pool(btrn, dest_size);
+	for (;;) {
+		char *buf;
+		size_t len = btr_next_buffer(btrn, &buf);
+		if (len >= dest_size)
+			return;
+		PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
+		if (merge_input(btrn) < 2)
+			return;
+	}
+}
+
+bool btr_eof(struct btr_node *btrn)
+{
+	char *buf;
+	size_t len = btr_next_buffer(btrn, &buf);
+
+	return (len == 0 && btr_no_parent(btrn));
+}
+
+void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
+{
+	struct btr_node *ch;
+	const char spaces[] = "                 ", *space = spaces + 16 - depth;
+
+	if (depth > 16)
+		return;
+	para_log(loglevel, "%s%s\n", space, btrn->name);
+	FOR_EACH_CHILD(ch, btrn)
+		log_tree_recursively(ch, loglevel, depth + 1);
+}
+
+void btr_log_tree(struct btr_node *btrn, int loglevel)
+{
+	return log_tree_recursively(btrn, loglevel, 0);
+}
+
+/*
+ * \return \a root if \a name is \p NULL.
+ */
+struct btr_node *btr_search_node(const char *name, struct btr_node *root)
+{
+	struct btr_node *ch;
+
+	if (!name)
+		return root;
+	if (!strcmp(root->name, name))
+		return root;
+	FOR_EACH_CHILD(ch, root) {
+		struct btr_node *result = btr_search_node(name, ch);
+		if (result)
+			return result;
+	}
+	return NULL;
+}
+
+/** 640K ought to be enough for everybody ;) */
+#define BTRN_MAX_PENDING (640 * 1024)
+
+int btr_node_status(struct btr_node *btrn, size_t min_iqs,
+	enum btr_node_type type)
+{
+	size_t iqs;
+
+	if (!btrn)
+		return 0;
+	if (type != BTR_NT_LEAF) {
+		if (btr_no_children(btrn))
+			return -E_BTR_NO_CHILD;
+		if (btr_bytes_pending(btrn) > BTRN_MAX_PENDING)
+			return 0;
+	}
+	if (type != BTR_NT_ROOT) {
+		if (btr_eof(btrn))
+			return -E_BTR_EOF;
+		iqs = btr_get_input_queue_size(btrn);
+		if (iqs == 0) /* we have a parent, because not eof */
+			return 0;
+		if (iqs < min_iqs && !btr_no_parent(btrn))
+			return 0;
+	}
+	return 1;
+}
+
+void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
+{
+	*tv = btrn->start;
+}