1 files changed, 457 insertions, 0 deletions
diff --git a/misc/apr_rmm.c b/misc/apr_rmm.c
new file mode 100644
index 0000000..1fd420b
--- /dev/null
+++ b/misc/apr_rmm.c
@@ -0,0 +1,457 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "apr_general.h"
+#include "apr_rmm.h"
+#include "apr_errno.h"
+#include "apr_lib.h"
+#include "apr_strings.h"
+
+/* The RMM region is made up of two doubly-linked-list of blocks; the
+ * list of used blocks, and the list of free blocks (either list may
+ * be empty).  The base pointer, rmm->base, points at the beginning of
+ * the shmem region in use.  Each block is addressable by an
+ * apr_rmm_off_t value, which represents the offset from the base
+ * pointer.  The term "address" is used here to mean such a value; an
+ * "offset from rmm->base".
+ *
+ * The RMM region contains exactly one "rmm_hdr_block_t" structure,
+ * the "header block", which is always stored at the base pointer.
+ * The firstused field in this structure is the address of the first
+ * block in the "used blocks" list; the firstfree field is the address
+ * of the first block in the "free blocks" list.
+ *
+ * Each block is prefixed by an "rmm_block_t" structure, followed by
+ * the caller-usable region represented by the block.  The next and
+ * prev fields of the structure are zero if the block is at the end or
+ * beginning of the linked-list respectively, or otherwise hold the
+ * address of the next and previous blocks in the list.  ("address 0",
+ * i.e. rmm->base is *not* a valid address for a block, since the
+ * header block is always stored at that address).
+ *
+ * At creation, the RMM region is initialized to hold a single block
+ * on the free list representing the entire available shm segment
+ * (minus header block); subsequent allocation and deallocation of
+ * blocks involves splitting blocks and coalescing adjacent blocks,
+ * and switching them between the free and used lists as
+ * appropriate. */
+
+typedef struct rmm_block_t {
+    apr_size_t size;
+    apr_rmm_off_t prev;
+    apr_rmm_off_t next;
+} rmm_block_t;
+
+/* Always at our apr_rmm_off(0):
+ */
+typedef struct rmm_hdr_block_t {
+    apr_size_t abssize;
+    apr_rmm_off_t /* rmm_block_t */ firstused;
+    apr_rmm_off_t /* rmm_block_t */ firstfree;
+} rmm_hdr_block_t;
+
+#define RMM_HDR_BLOCK_SIZE (APR_ALIGN_DEFAULT(sizeof(rmm_hdr_block_t)))
+#define RMM_BLOCK_SIZE (APR_ALIGN_DEFAULT(sizeof(rmm_block_t)))
+
+struct apr_rmm_t {
+    apr_pool_t *p;
+    rmm_hdr_block_t *base;
+    apr_size_t size;
+    apr_anylock_t lock;
+};
+
+static apr_rmm_off_t find_block_by_offset(apr_rmm_t *rmm, apr_rmm_off_t next, 
+                                          apr_rmm_off_t find, int includes)
+{
+    apr_rmm_off_t prev = 0;
+
+    while (next) {
+        struct rmm_block_t *blk = (rmm_block_t*)((char*)rmm->base + next);
+
+        if (find == next)
+            return next;
+
+        /* Overshot? */
+        if (find < next)
+            return includes ? prev : 0;
+
+        prev = next;
+        next = blk->next;
+    }
+    return includes ? prev : 0;
+}
+
+static apr_rmm_off_t find_block_of_size(apr_rmm_t *rmm, apr_size_t size)
+{
+    apr_rmm_off_t next = rmm->base->firstfree;
+    apr_rmm_off_t best = 0;
+    apr_rmm_off_t bestsize = 0;
+
+    while (next) {
+        struct rmm_block_t *blk = (rmm_block_t*)((char*)rmm->base + next);
+
+        if (blk->size == size)
+            return next;
+
+        if (blk->size >= size) {
+            /* XXX: sub optimal algorithm 
+             * We need the most thorough best-fit logic, since we can
+             * never grow our rmm, we are SOL when we hit the wall.
+             */
+            if (!bestsize || (blk->size < bestsize)) {
+                bestsize = blk->size;
+                best = next;
+            }
+        }
+
+        next = blk->next;
+    }
+
+    if (bestsize > RMM_BLOCK_SIZE + size) {
+        struct rmm_block_t *blk = (rmm_block_t*)((char*)rmm->base + best);
+        struct rmm_block_t *new = (rmm_block_t*)((char*)rmm->base + best + size);
+
+        new->size = blk->size - size;
+        new->next = blk->next;
+        new->prev = best;
+
+        blk->size = size;
+        blk->next = best + size;
+
+        if (new->next) {
+            blk = (rmm_block_t*)((char*)rmm->base + new->next);
+            blk->prev = best + size;
+        }
+    }
+
+    return best;
+}
+
+static void move_block(apr_rmm_t *rmm, apr_rmm_off_t this, int free)
+{   
+    struct rmm_block_t *blk = (rmm_block_t*)((char*)rmm->base + this);
+
+    /* close the gap */
+    if (blk->prev) {
+        struct rmm_block_t *prev = (rmm_block_t*)((char*)rmm->base + blk->prev);
+        prev->next = blk->next;
+    }
+    else {
+        if (free) {
+            rmm->base->firstused = blk->next;
+        }
+        else {
+            rmm->base->firstfree = blk->next;
+        }
+    }
+    if (blk->next) {
+        struct rmm_block_t *next = (rmm_block_t*)((char*)rmm->base + blk->next);
+        next->prev = blk->prev;
+    }
+
+    /* now find it in the other list, pushing it to the head if required */
+    if (free) {
+        blk->prev = find_block_by_offset(rmm, rmm->base->firstfree, this, 1);
+        if (!blk->prev) {
+            blk->next = rmm->base->firstfree;
+            rmm->base->firstfree = this;
+        }
+    }
+    else {
+        blk->prev = find_block_by_offset(rmm, rmm->base->firstused, this, 1);
+        if (!blk->prev) {
+            blk->next = rmm->base->firstused;
+            rmm->base->firstused = this;
+        }
+    }
+
+    /* and open it up */
+    if (blk->prev) {
+        struct rmm_block_t *prev = (rmm_block_t*)((char*)rmm->base + blk->prev);
+        if (free && (blk->prev + prev->size == this)) {
+            /* Collapse us into our predecessor */
+            prev->size += blk->size;
+            this = blk->prev;
+            blk = prev;
+        }
+        else {
+            blk->next = prev->next;
+            prev->next = this;
+        }
+    }
+
+    if (blk->next) {
+        struct rmm_block_t *next = (rmm_block_t*)((char*)rmm->base + blk->next);
+        if (free && (this + blk->size == blk->next)) {
+            /* Collapse us into our successor */
+            blk->size += next->size;
+            blk->next = next->next;
+            if (blk->next) {
+                next = (rmm_block_t*)((char*)rmm->base + blk->next);
+                next->prev = this;
+            }
+        }
+        else {
+            next->prev = this;
+        }
+    }
+}
+
+APU_DECLARE(apr_status_t) apr_rmm_init(apr_rmm_t **rmm, apr_anylock_t *lock, 
+                                       void *base, apr_size_t size,
+                                       apr_pool_t *p)
+{
+    apr_status_t rv;
+    rmm_block_t *blk;
+    apr_anylock_t nulllock;
+    
+    if (!lock) {
+        nulllock.type = apr_anylock_none;
+        nulllock.lock.pm = NULL;
+        lock = &nulllock;
+    }
+    if ((rv = APR_ANYLOCK_LOCK(lock)) != APR_SUCCESS)
+        return rv;
+
+    (*rmm) = (apr_rmm_t *)apr_pcalloc(p, sizeof(apr_rmm_t));
+    (*rmm)->p = p;
+    (*rmm)->base = base;
+    (*rmm)->size = size;
+    (*rmm)->lock = *lock;
+
+    (*rmm)->base->abssize = size;
+    (*rmm)->base->firstused = 0;
+    (*rmm)->base->firstfree = RMM_HDR_BLOCK_SIZE;
+
+    blk = (rmm_block_t *)((char*)base + (*rmm)->base->firstfree);
+
+    blk->size = size - (*rmm)->base->firstfree;
+    blk->prev = 0;
+    blk->next = 0;
+
+    return APR_ANYLOCK_UNLOCK(lock);
+}
+
+APU_DECLARE(apr_status_t) apr_rmm_destroy(apr_rmm_t *rmm)
+{
+    apr_status_t rv;
+    rmm_block_t *blk;
+
+    if ((rv = APR_ANYLOCK_LOCK(&rmm->lock)) != APR_SUCCESS) {
+        return rv;
+    }
+    /* Blast it all --- no going back :) */
+    if (rmm->base->firstused) {
+        apr_rmm_off_t this = rmm->base->firstused;
+        do {
+            blk = (rmm_block_t *)((char*)rmm->base + this);
+            this = blk->next;
+            blk->next = blk->prev = 0;
+        } while (this);
+        rmm->base->firstused = 0;
+    }
+    if (rmm->base->firstfree) {
+        apr_rmm_off_t this = rmm->base->firstfree;
+        do {
+            blk = (rmm_block_t *)((char*)rmm->base + this);
+            this = blk->next;
+            blk->next = blk->prev = 0;
+        } while (this);
+        rmm->base->firstfree = 0;
+    }
+    rmm->base->abssize = 0;
+    rmm->size = 0;
+
+    return APR_ANYLOCK_UNLOCK(&rmm->lock);
+}
+
+APU_DECLARE(apr_status_t) apr_rmm_attach(apr_rmm_t **rmm, apr_anylock_t *lock,
+                                         void *base, apr_pool_t *p)
+{
+    apr_anylock_t nulllock;
+
+    if (!lock) {
+        nulllock.type = apr_anylock_none;
+        nulllock.lock.pm = NULL;
+        lock = &nulllock;
+    }
+
+    /* sanity would be good here */
+    (*rmm) = (apr_rmm_t *)apr_pcalloc(p, sizeof(apr_rmm_t));
+    (*rmm)->p = p;
+    (*rmm)->base = base;
+    (*rmm)->size = (*rmm)->base->abssize;
+    (*rmm)->lock = *lock;
+    return APR_SUCCESS;
+}
+
+APU_DECLARE(apr_status_t) apr_rmm_detach(apr_rmm_t *rmm) 
+{
+    /* A noop until we introduce locked/refcounts */
+    return APR_SUCCESS;
+}
+
+APU_DECLARE(apr_rmm_off_t) apr_rmm_malloc(apr_rmm_t *rmm, apr_size_t reqsize)
+{
+    apr_size_t size;
+    apr_rmm_off_t this;
+    
+    size = APR_ALIGN_DEFAULT(reqsize) + RMM_BLOCK_SIZE;
+    if (size < reqsize) {
+        return 0;
+    }
+
+    APR_ANYLOCK_LOCK(&rmm->lock);
+
+    this = find_block_of_size(rmm, size);
+
+    if (this) {
+        move_block(rmm, this, 0);
+        this += RMM_BLOCK_SIZE;
+    }
+
+    APR_ANYLOCK_UNLOCK(&rmm->lock);
+    return this;
+}
+
+APU_DECLARE(apr_rmm_off_t) apr_rmm_calloc(apr_rmm_t *rmm, apr_size_t reqsize)
+{
+    apr_size_t size;
+    apr_rmm_off_t this;
+        
+    size = APR_ALIGN_DEFAULT(reqsize) + RMM_BLOCK_SIZE;
+    if (size < reqsize) {
+        return 0;
+    }
+
+    APR_ANYLOCK_LOCK(&rmm->lock);
+
+    this = find_block_of_size(rmm, size);
+
+    if (this) {
+        move_block(rmm, this, 0);
+        this += RMM_BLOCK_SIZE;
+        memset((char*)rmm->base + this, 0, size - RMM_BLOCK_SIZE);
+    }
+
+    APR_ANYLOCK_UNLOCK(&rmm->lock);
+    return this;
+}
+
+APU_DECLARE(apr_rmm_off_t) apr_rmm_realloc(apr_rmm_t *rmm, void *entity,
+                                           apr_size_t reqsize)
+{
+    apr_rmm_off_t this;
+    apr_rmm_off_t old;
+    struct rmm_block_t *blk;
+    apr_size_t size, oldsize;
+
+    if (!entity) {
+        return apr_rmm_malloc(rmm, reqsize);
+    }
+
+    size = APR_ALIGN_DEFAULT(reqsize);
+    if (size < reqsize) {
+        return 0;
+    }
+    old = apr_rmm_offset_get(rmm, entity);
+
+    if ((this = apr_rmm_malloc(rmm, size)) == 0) {
+        return 0;
+    }
+
+    blk = (rmm_block_t*)((char*)rmm->base + old - RMM_BLOCK_SIZE);
+    oldsize = blk->size;
+
+    memcpy(apr_rmm_addr_get(rmm, this),
+           apr_rmm_addr_get(rmm, old), oldsize < size ? oldsize : size);
+    apr_rmm_free(rmm, old);
+
+    return this;
+}
+
+APU_DECLARE(apr_status_t) apr_rmm_free(apr_rmm_t *rmm, apr_rmm_off_t this)
+{
+    apr_status_t rv;
+    struct rmm_block_t *blk;
+
+    /* A little sanity check is always healthy, especially here.
+     * If we really cared, we could make this compile-time
+     */
+    if (this < RMM_HDR_BLOCK_SIZE + RMM_BLOCK_SIZE) {
+        return APR_EINVAL;
+    }
+
+    this -= RMM_BLOCK_SIZE;
+
+    blk = (rmm_block_t*)((char*)rmm->base + this);
+
+    if ((rv = APR_ANYLOCK_LOCK(&rmm->lock)) != APR_SUCCESS) {
+        return rv;
+    }
+    if (blk->prev) {
+        struct rmm_block_t *prev = (rmm_block_t*)((char*)rmm->base + blk->prev);
+        if (prev->next != this) {
+            APR_ANYLOCK_UNLOCK(&rmm->lock);
+            return APR_EINVAL;
+        }
+    }
+    else {
+        if (rmm->base->firstused != this) {
+            APR_ANYLOCK_UNLOCK(&rmm->lock);
+            return APR_EINVAL;
+        }
+    }
+
+    if (blk->next) {
+        struct rmm_block_t *next = (rmm_block_t*)((char*)rmm->base + blk->next);
+        if (next->prev != this) {
+            APR_ANYLOCK_UNLOCK(&rmm->lock);
+            return APR_EINVAL;
+        }
+    }
+
+    /* Ok, it remained [apparently] sane, so unlink it
+     */
+    move_block(rmm, this, 1);
+    
+    return APR_ANYLOCK_UNLOCK(&rmm->lock);
+}
+
+APU_DECLARE(void *) apr_rmm_addr_get(apr_rmm_t *rmm, apr_rmm_off_t entity) 
+{
+    /* debug-sanity checking here would be good
+     */
+    return (void*)((char*)rmm->base + entity);
+}
+
+APU_DECLARE(apr_rmm_off_t) apr_rmm_offset_get(apr_rmm_t *rmm, void* entity)
+{
+    /* debug, or always, sanity checking here would be good
+     * since the primitive is apr_rmm_off_t, I don't mind penalizing
+     * inverse conversions for safety, unless someone can prove that
+     * there is no choice in some cases.
+     */
+    return ((char*)entity - (char*)rmm->base);
+}
+
+APU_DECLARE(apr_size_t) apr_rmm_overhead_get(int n) 
+{
+    /* overhead per block is at most APR_ALIGN_DEFAULT(1) wasted bytes
+     * for alignment overhead, plus the size of the rmm_block_t
+     * structure. */
+    return RMM_HDR_BLOCK_SIZE + n * (RMM_BLOCK_SIZE + APR_ALIGN_DEFAULT(1));
+}