From a8b190d5f733a97e0cdfe8209e05a2c1e0ac11e7 Mon Sep 17 00:00:00 2001
From: Robin Mueller <robin.mueller.m@gmail.com>
Date: Sat, 11 Jun 2022 17:43:47 +0200
Subject: [PATCH] init pool

---
 src/core/pool.rs | 164 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)

diff --git a/src/core/pool.rs b/src/core/pool.rs
index 8b13789..9b8ebab 100644
--- a/src/core/pool.rs
+++ b/src/core/pool.rs
@@ -1 +1,165 @@
+type NumBuckets = u16;
 
+pub struct PoolCfg {
+    cfg: Vec<(NumBuckets, usize)>,
+}
+
+impl PoolCfg {
+    pub fn add_pool(&mut self, num_elems: NumBuckets, elem_size: usize) {
+        self.cfg.push((num_elems, elem_size))
+    }
+
+    fn order(&mut self) -> usize {
+        self.cfg.sort_unstable();
+        self.cfg.len()
+    }
+}
+
+type PoolSize = usize;
+
+pub struct LocalPool {
+    pool_cfg: PoolCfg,
+    pool: Vec<Vec<u8>>,
+    sizes_lists: Vec<Vec<PoolSize>>,
+}
+
+#[derive(Debug)]
+pub struct StoreAddr {
+    pool_idx: u16,
+    packet_idx: NumBuckets,
+}
+
+impl StoreAddr {
+    pub const INVALID_ADDR: u32 = 0xFFFFFFFF;
+
+    pub fn raw(&self) -> u32 {
+        ((self.pool_idx as u32) << 16) as u32 | self.packet_idx as u32
+    }
+}
+
+pub enum StoreError {
+    DataTooLarge(usize),
+    InvalidSubpool(u16),
+    StoreFull(u16),
+    InvalidStoreId(StoreAddr),
+    InternalError(String),
+}
+
+impl LocalPool {
+    const STORE_FREE: PoolSize = PoolSize::MAX;
+    const MAX_SIZE: PoolSize = Self::STORE_FREE - 1;
+
+    pub fn new(mut cfg: PoolCfg) -> LocalPool {
+        let subpools_num = cfg.order();
+        let mut local_pool = LocalPool {
+            pool_cfg: cfg,
+            pool: Vec::with_capacity(subpools_num),
+            sizes_lists: Vec::with_capacity(subpools_num),
+        };
+        for &(num_elems, elem_size) in local_pool.pool_cfg.cfg.iter() {
+            let next_pool_len = elem_size * num_elems as usize;
+            local_pool.pool.push(vec![0; next_pool_len]);
+            let next_sizes_list_len = num_elems as usize;
+            local_pool.sizes_lists.push(vec![Self::STORE_FREE; next_sizes_list_len]);
+        }
+        local_pool
+    }
+
+    pub fn add(&mut self, data: &[u8]) -> Result<StoreAddr, StoreError> {
+        if data.len() > Self::MAX_SIZE {
+            return Err(StoreError::DataTooLarge(data.len()));
+        }
+        self.reserve(data)?;
+        let addr = StoreAddr {
+            packet_idx: 0,
+            pool_idx: 0,
+        };
+        self.write(&addr, data)?;
+        Ok(addr)
+    }
+
+    pub fn free_element(&mut self) -> Result<(StoreAddr, &mut [u8]), StoreError> {
+        Ok((
+            StoreAddr {
+                packet_idx: 0,
+                pool_idx: 0,
+            },
+            self.pool[0].as_mut_slice(),
+        ))
+    }
+
+    pub fn get(&self, _addr: StoreAddr) -> Result<&[u8], StoreError> {
+        Ok(self.pool[0].as_slice())
+    }
+
+    pub fn modify(&mut self, _addr: StoreAddr) -> Result<&mut [u8], StoreError> {
+        Ok(self.pool[0].as_mut_slice())
+    }
+
+    pub fn delete(&mut self, _addr: StoreAddr) -> Result<(), StoreError> {
+        Ok(())
+    }
+
+    fn reserve(&mut self, data: &[u8]) -> Result<StoreAddr, StoreError> {
+        let subpool_idx = self.find_subpool(data.len(), 0)?;
+        let (slot, size_slot_ref) = self.find_empty(subpool_idx)?;
+        *size_slot_ref = data.len();
+        Ok(StoreAddr {
+            pool_idx: subpool_idx,
+            packet_idx: slot,
+        })
+    }
+
+    fn find_subpool(&self, req_size: usize, start_at_subpool: u16) -> Result<u16, StoreError> {
+        for (i, &(_, elem_size)) in self.pool_cfg.cfg.iter().enumerate() {
+            if i < start_at_subpool as usize {
+                continue;
+            }
+            if elem_size >= req_size {
+                return Ok(i as u16);
+            }
+        }
+        Err(StoreError::DataTooLarge(req_size))
+    }
+
+    fn write(&mut self, addr: &StoreAddr, data: &[u8]) -> Result<(), StoreError> {
+        let packet_pos = self
+            .raw_pos(addr)
+            .ok_or_else(||{
+                StoreError::InternalError(format!(
+                    "write: Error in raw_pos func with address {:?}",
+                    addr
+                ))
+            })?;
+        let subpool =
+            self.pool
+                .get_mut(addr.pool_idx as usize)
+                .ok_or_else(||{
+                    StoreError::InternalError(format!(
+                        "write: Error retrieving pool slice with address {:?}",
+                        addr
+                    ))
+                })?;
+        let pool_slice = &mut subpool[packet_pos..self.pool_cfg.cfg[addr.pool_idx as usize].1];
+        pool_slice.copy_from_slice(data);
+        Ok(())
+    }
+
+    fn find_empty(&mut self, subpool: u16) -> Result<(u16, &mut usize), StoreError> {
+        if let Some(size_list) = self.sizes_lists.get_mut(subpool as usize) {
+            for (i, elem_size) in size_list.iter_mut().enumerate() {
+                if *elem_size == Self::STORE_FREE {
+                    return Ok((i as u16, elem_size));
+                }
+            }
+        } else {
+            return Err(StoreError::InvalidSubpool(subpool));
+        }
+        Err(StoreError::StoreFull(subpool))
+    }
+
+    fn raw_pos(&self, addr: &StoreAddr) -> Option<usize> {
+        let (_, size) = self.pool_cfg.cfg.get(addr.pool_idx as usize)?;
+        Some(addr.packet_idx as usize * size)
+    }
+}